Chromium

The majority of the time is spent creating PlainTextRanges multiple times on every input.

xiaochengh@, could you take look? yet another speed issue.

I indeed observed some lags compared to Safari and Firefox, but cannot reproduce those huge lags at sec level as reported in #1. My tests were done on Linux ToT (50.0.2637.0) and OSX Canary (50.0.2636.0). I got consistent result as stated below.

Typing each letter took ~100ms (which is slow compared to the other browsers). I could not identify a unique root cause of the lag, though. Some slow operations are |FrameView::layout| and |ThreadProxy::BeginMainFrame|, which constituted ~1/3 of the overall running time.

xiaochengh, from my profile results, it looks like there is no single root cause, just multiple instances of duplicated work. Is that what you are seeing too?

pdr@: I'm not sure if it's duplicated work as I didn't see the same function called for multiple times in one typing operation.

There is still a lot of blank space in the profiling result. We need more traces.

I added trace events to TextIterator::createPlainText and PlainTextRange::create* and recorded a trace. In the attached trace you can see the multiple calls to create ranges for just a single input.

I see. That is consistent with what I observed.

I'll handle it.

Thanks for the excellent report!

Hi guys,

We run a service called Remember The Milk, and we're seeing a similar, but not identical issue. I don't know what to do about it -- but it's affecting some of our users ability to use our web app...

It seems that if a (e.g.) Japanese user tries to type more than 15 Japanese characters into our "Smart Add" field (which is a fancy contenteditable), Chrome starts using 100% of CPU doing what appears to be nothing. Moving the cursor in the field is extremely slow, and bluring the field does not help -- the entire page becomes quite unresponsive.

This string works fine (no slow down):

すべてのタスクすべてのタスクす

But this string causes Chrome to freak out:

すべてのタスクすべてのタスクすべ

I've tried to isolate the issue and it seems to only happen on:

Chrome 48.0.2564.109 (64-bit) running on OS X 10.11.3.

It doesn't happen on Chrome 49 or 50 on OS X.

It doesn't happen on Chrome 48 running Ubuntu, or Windows 10.

I don't know if it's related to this issue or not, but I thought I'd mention it -- I've been trying to find a work around without much success.

Thanks!

Ah, one thing I forgot to mention is that adding a space in the middle of the string fixes it. I.e.:

BAD: すべてのタスクすべてのタスクすべ

GOOD: すべてのタスク すべてのタスクすべ

No idea why.

omar.kilani: I tried to reproduce with <div contenteditable="true"> but failed. The OS and Chrome version are the same as in your report. Maybe it requires a more complicated test case?

It also seems to be an already fixed issue, as it doesn't reproduce with Chrome 49 or 50.

yosin@: What do we need to do for such cases?

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I see this as well. What I find to be a good check is to try holding down a key, and let it auto repeat. On Firefox, it'll just repeat. On Chrom(ium), you get multiple letters at a time, and then input continues on after you let up on the key.

I was running into this bug trying to make a textbox autoresize. I note that I can't do it using javascript on a textarea (using the input event and scrollHeight), and I can't do it using a contenteditable div. Both lag tremendously, and the lag only gets worse the more you type.

I mention this, in case one is connected to the other.

Hi all
Windows 10, Chrome 57.0.2987.133 (64-bit)
I can reproduce test mentioned in #1 http://jsbin.com/mifaro
Plus, I've made perhaps a less obvious test-case - took a wikipedia article about NASA and copied it into <div contenteditable="true"> and compared text editing withing the article Chrome VS Firefox.
Here is youtube video of my fast typing https://youtu.be/goka0_Z-RLo
Attached is a file I used for tests.

Similar behavior is seen on macOS.

Safari and Firefox are lightning fast compared to Chrome when it comes to editing text in contenteditable div.

If I can be of more help solving this issue - please, do let me know.

Whoops, we missed this one in our meta issue.

Hi, any plans on this one? Like deadlines or something? It's really a work-stopper.

Editing code has changed a lot since this bug was reported. On the latest Canary (60.0.3073.0), with http://jsbin.com/mifaro, tracing shows that the slowness is due to:
1. Typing each character requires clean layout
2. Each layout update takes a long time

With the current architecture, it's hard to improve the performance by locally optimizing some small piece of code -- Basically all editing code requires clean layout, and one layout update can't be further reduced.

We have a re-architecture project for editing code, which should give us some possibilities to fix this issue. See https://crbug.com/chromium/707656.

[Comment Deleted]

And this approximates us to dates like... 2017...? 2018? :)
Thanks!

P.S.
Wouldn't it make sense to do at least something similar to JS's debounce or throttle on such events like keypress/charinput?

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2018 and it still the same...

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Since the slowdown comes from layouting in block, separating a content
into multiple divs is a workaround:
<div contenteditable>
 <div>so much characters,,, </div>
 <div>let user edit here</div>
</div>

On that, input latency takes about 26 milliseconds on latest canary
(Version 69.0.3460.0), which is 10x faster than the one w/o the workaround.

Found out that Chromium(and Chrome) is also A LOT(really really LOT) slower to paste a huge text in those content editable elements than other browsers.

While others(like edge) would paste the whole text(2 million characters) in a second, keeping the page responsive while waiting the text be completely loaded, chrome/Chromium didn't in over 1 minute, and the page freezes.

CPU performance analysis by VS2018

Function Name   Total CPU [unit, %]     Self CPU [unit, %]      Module
| - base::RunLoop::Run  53024 (92.54%)  0 (0.00%)       content_shell.exe
| - base::`anonymous namespace'::ThreadFunc     52933 (92.39%)  0 (0.00%)       content_shell.exe
| - base::debug::TaskAnnotator::RunTask 52668 (91.92%)  10 (0.02%)      content_shell.exe
| - base::MessagePumpWin::Run   52430 (91.51%)  0 (0.00%)       content_shell.exe
| - base::Thread::ThreadMain    52385 (91.43%)  0 (0.00%)       content_shell.exe
| - base::MessageLoop::RunTask  52327 (91.33%)  6 (0.01%)       content_shell.exe
| - base::MessagePumpForUI::DoRunLoop   51562 (89.99%)  5 (0.01%)       content_shell.exe
| - base::sequence_manager::internal::ThreadControllerImpl::DoWork      50702 (88.49%)  3 (0.01%)       content_shell.exe
| - content::QueuedWebInputEvent::Dispatch      46971 (81.98%)  0 (0.00%)       content_shell.exe
| - content::MainThreadEventQueue::HandleEventOnMainThread      46969 (81.98%)  0 (0.00%)       content_shell.exe
| - content::RenderWidget::HandleInputEvent     46969 (81.98%)  0 (0.00%)       content_shell.exe
| - content::RenderWidgetInputHandler::HandleInputEvent 46968 (81.97%)  1 (0.00%)       content_shell.exe
| - blink::WebViewImpl::HandleInputEvent        46915 (81.88%)  0 (0.00%)       content_shell.exe
| - blink::PageWidgetDelegate::HandleInputEvent 46913 (81.88%)  0 (0.00%)       content_shell.exe
| - blink::EventDispatcher::DispatchEvent       46808 (81.70%)  1 (0.00%)       content_shell.exe
| - blink::KeyboardEventManager::KeyEvent       46805 (81.69%)  1 (0.00%)       content_shell.exe
| - blink::EventDispatcher::Dispatch    46799 (81.68%)  1 (0.00%)       content_shell.exe
| - blink::EventDispatcher::DispatchEventPostProcess    46792 (81.67%)  1 (0.00%)       content_shell.exe
| - blink::WebViewImpl::HandleCharEvent 46792 (81.67%)  0 (0.00%)       content_shell.exe
| - blink::KeyboardEventManager::DefaultKeyboardEventHandler    46791 (81.67%)  1 (0.00%)       content_shell.exe
| - blink::Editor::HandleEditingKeyboardEvent   46790 (81.66%)  0 (0.00%)       content_shell.exe
| - blink::Editor::HandleKeyboardEvent  46790 (81.66%)  0 (0.00%)       content_shell.exe
| - blink::EventHandler::HandleTextInputEvent   46778 (81.64%)  0 (0.00%)       content_shell.exe
| - blink::Editor::HandleTextEvent      46776 (81.64%)  0 (0.00%)       content_shell.exe
| - blink::EventHandler::DefaultTextInputEventHandler   46776 (81.64%)  0 (0.00%)       content_shell.exe
| - blink::Editor::InsertTextWithoutSendingTextEvent    46775 (81.64%)  0 (0.00%)       content_shell.exe
| - blink::TypingCommand::InsertText    46757 (81.61%)  1 (0.00%)       content_shell.exe
| - content::MainThreadEventQueue::DispatchEvents       46067 (80.40%)  0 (0.00%)       content_shell.exe
| - blink::TypingCommand::InsertTextInternal    44085 (76.94%)  1 (0.00%)       content_shell.exe
| - blink::LocalFrameView::UpdateLayout 34800 (60.74%)  0 (0.00%)       content_shell.exe
| - blink::Document::UpdateStyleAndLayout       34798 (60.73%)  0 (0.00%)       content_shell.exe
| - blink::LocalFrameView::PerformLayout        34790 (60.72%)  0 (0.00%)       content_shell.exe
| - blink::LayoutBlock::UpdateLayout    34786 (60.71%)  0 (0.00%)       content_shell.exe
| - blink::LayoutBlockFlow::UpdateBlockLayout   34784 (60.71%)  1 (0.00%)       content_shell.exe
| - blink::LocalFrameView::LayoutFromRootObject 34769 (60.68%)  0 (0.00%)       content_shell.exe
| - blink::LayoutBlockFlow::LayoutChildren      34642 (60.46%)  0 (0.00%)       content_shell.exe
| - blink::LayoutBlockFlow::LayoutInlineChildren        34641 (60.46%)  0 (0.00%)       content_shell.exe
| - blink::LayoutBlockFlow::LayoutRunsAndFloats 34563 (60.32%)  0 (0.00%)       content_shell.exe
| - blink::LayoutBlockFlow::LayoutRunsAndFloatsInRange  34554 (60.31%)  29 (0.05%)      content_shell.exe
| - blink::PaintLayer::UpdateSizeAndScrollingAfterLayout        33731 (58.87%)  1 (0.00%)       content_shell.exe
| - blink::PaintLayerScrollableArea::UpdateAfterLayout  33729 (58.87%)  0 (0.00%)       content_shell.exe
| - blink::LineBreaker::NextLineBreak   33495 (58.46%)  9 (0.02%)       content_shell.exe
| - blink::BreakingContext::HandleText  33369 (58.24%)  542 (0.95%)     content_shell.exe
| - blink::InsertTextCommand::DoApply   33195 (57.94%)  1 (0.00%)       content_shell.exe
| - blink::CompositeEditCommand::ApplyCommandToComposite        33195 (57.94%)  0 (0.00%)       content_shell.exe
| - blink::TypingCommand::InsertTextRunWithoutNewlines  33195 (57.94%)  0 (0.00%)       content_shell.exe
| - blink::Document::UpdateStyleAndLayoutIgnorePendingStylesheets       33182 (57.91%)  0 (0.00%)       content_shell.exe
| - blink::CompositeEditCommand::RebalanceWhitespaceAt  33172 (57.90%)  0 (0.00%)       content_shell.exe
| - blink::CompositeEditCommand::CanRebalance   33171 (57.89%)  0 (0.00%)       content_shell.exe
| - base::MessageLoop::DoDelayedWork    31783 (55.47%)  1 (0.00%)       content_shell.exe
| - blink::CachingWordShapeIterator::ShapeToEndIndex    30542 (53.31%)  180 (0.31%)     content_shell.exe
| - blink::CachingWordShapeIterator::ShapeWord  30341 (52.95%)  55 (0.10%)      content_shell.exe
| - blink::CachingWordShapeIterator::ShapeWordWithoutSpacing    30279 (52.85%)  95 (0.17%)      content_shell.exe
| - blink::HarfBuzzShaper::Shape        29374 (51.27%)  3 (0.01%)       content_shell.exe
| - blink::HarfBuzzShaper::Shape        29371 (51.26%)  49 (0.09%)      content_shell.exe
| - blink::HarfBuzzShaper::ShapeSegment 23560 (41.12%)  79 (0.14%)      content_shell.exe
| - base::MessageLoop::DoWork   20616 (35.98%)  12 (0.02%)      content_shell.exe
| - hb_shape    18541 (32.36%)  2 (0.00%)       content_shell.exe
| - hb_shape_full       18539 (32.36%)  5 (0.01%)       content_shell.exe
| - hb_shape_plan_execute       18501 (32.29%)  6 (0.01%)       content_shell.exe
| - _hb_ot_shape        18493 (32.28%)  203 (0.35%)     content_shell.exe
| - blink::TextIteratorAlgorithm<blink::EditingAlgorithm<blink::NodeTraversal> >::Advance       16159 (28.20%)  23 (0.04%)      content_shell.exe
| - blink::TextIteratorTextNodeHandler::HandleTextBox   16087 (28.08%)  205 (0.36%)     content_shell.exe
| - blink::TextIteratorTextNodeHandler::HandleRemainingTextRuns 16068 (28.04%)  27 (0.05%)      content_shell.exe
| - memchr      15567 (27.17%)  15565 (27.17%)  content_shell.exe
| - blink::Font::Width  13255 (23.13%)  55 (0.10%)      content_shell.exe
| - blink::CachingWordShaper::Width     12815 (22.37%)  117 (0.20%)     content_shell.exe
| - hb_font_get_glyph_h_advances_default        12676 (22.12%)  128 (0.22%)     content_shell.exe
| - blink::HarfBuzzGetGlyphHorizontalAdvance    12544 (21.89%)  231 (0.40%)     content_shell.exe
| - SkPaint::getTextWidths      12454 (21.74%)  926 (1.62%)     content_shell.exe
| - blink::SkiaTextMetrics::GetGlyphWidthForHarfBuzz    12097 (21.11%)  526 (0.92%)     content_shell.exe
| - WTF::String::find   11804 (20.60%)  27 (0.05%)      content_shell.exe
| - blink::BreakingContext::CalculateWordWidth  11282 (19.69%)  10 (0.02%)      content_shell.exe
| - blink::Editor::RespondToChangedSelection    10953 (19.12%)  0 (0.00%)       content_shell.exe
| - blink::FrameSelection::SetSelection 10953 (19.12%)  0 (0.00%)       content_shell.exe
| - blink::FrameSelection::SetSelectionDeprecated       10953 (19.12%)  0 (0.00%)       content_shell.exe
| - blink::CompositeEditCommand::AppliedEditing 10889 (19.00%)  0 (0.00%)       content_shell.exe
| - blink::ChangeSelectionAfterCommand  10882 (18.99%)  0 (0.00%)       content_shell.exe
| - blink::Font::SelectionRectForText   10350 (18.06%)  6 (0.01%)       content_shell.exe
| - blink::CachingWordShaper::GetCharacterRange 10312 (18.00%)  10 (0.02%)      content_shell.exe
| - content::RenderWidget::UpdateTextInputStateInternal 9910 (17.30%)   1 (0.00%)       content_shell.exe
| - blink::InputMethodController::TextInputInfo 9679 (16.89%)   0 (0.00%)       content_shell.exe
| - blink::WebInputMethodControllerImpl::TextInputInfo  9679 (16.89%)   0 (0.00%)       content_shell.exe
| - blink::PlainTextRange::Create       9109 (15.90%)   0 (0.00%)       content_shell.exe
| - blink::TextIteratorAlgorithm<blink::EditingAlgorithm<blink::NodeTraversal> >::RangeLength   9108 (15.90%)   5 (0.01%)       content_shell.exe
| - blink::Font::OffsetForPosition      8932 (15.59%)   4 (0.01%)       content_shell.exe
| - blink::CachingWordShaper::OffsetForPosition 8913 (15.56%)   4 (0.01%)       content_shell.exe
| - content::RenderFrameImpl::DidChangeSelection        6906 (12.05%)   0 (0.00%)       content_shell.exe
| - SkStrikeCache::FindOrCreateStrikeExclusive  6548 (11.43%)   108 (0.19%)     content_shell.exe
| - blink::`anonymous namespace'::PlainTextRangeForEphemeralRange       6450 (11.26%)   0 (0.00%)       content_shell.exe
| - SkStrikeCache::FindOrCreateStrikeExclusive  6443 (11.25%)   777 (1.36%)     content_shell.exe
| - blink::PlainText    5893 (10.29%)   2 (0.00%)       content_shell.exe
| - blink::RunSegmenter::Consume        5312 (9.27%)    8 (0.01%)       content_shell.exe
| - content::RenderFrameImpl::SyncSelectionIfRequired   4047 (7.06%)    0 (0.00%)       content_shell.exe
| - blink::TextIteratorTextNodeHandler::EmitText        4009 (7.00%)    66 (0.12%)      content_shell.exe
| - base::internal::Invoker<base::internal::BindState<void (cc::ProxyMain::*)(std::unique_ptr<cc::BeginMainFrameAndCommitState,std::default_delete<cc::BeginMainFrameAndCommitState> >),base::WeakPtr<cc::ProxyMain>,base::internal::PassedWrapper<std::unique_ptr<cc::BeginMainFrameAndCommitState,std::default_delete<cc::BeginMainFrameAndCommitState> > > >,void ()>::RunOnce       4006 (6.99%)    0 (0.00%)       content_shell.exe
| - cc::ProxyMain::BeginMainFrame       4006 (6.99%)    0 (0.00%)       content_shell.exe
| - SkScalerContext::CreateDescriptorAndEffectsUsingPaint       3835 (6.69%)    213 (0.37%)     content_shell.exe
| - WTF::String::Replace        3809 (6.65%)    9 (0.02%)       content_shell.exe
| - WTF::StringImpl::Replace    3800 (6.63%)    9 (0.02%)       content_shell.exe
| - blink::HarfBuzzShaper::ExtractShapeResults  3640 (6.35%)    85 (0.15%)      content_shell.exe
| - blink::HarfBuzzShaper::CommitGlyphs 3550 (6.20%)    11 (0.02%)      content_shell.exe
| - blink::ShapeResult::InsertRun       3442 (6.01%)    8 (0.01%)       content_shell.exe
| - blink::ShapeResult::ComputeGlyphPositions<1>        3360 (5.86%)    315 (0.55%)     content_shell.exe
| - blink::RunSegmenter::ConsumeScriptIteratorPastLastSplit     3137 (5.48%)    4 (0.01%)       content_shell.exe
| - blink::ScriptRunIterator::Consume   3133 (5.47%)    107 (0.19%)     content_shell.exe
| - content::RenderWidget::WillBeginCompositorFrame     2972 (5.19%)    0 (0.00%)       content_shell.exe
| - blink::ShapeResult::ComputeGlyphBounds<1>   2881 (5.03%)    196 (0.34%)     content_shell.exe
| - _hb_ot_shape_normalize      2876 (5.02%)    591 (1.03%)     content_shell.exe
| - blink::InputMethodController::GetSelectionOffsets   2663 (4.65%)    0 (0.00%)       content_shell.exe
| - blink::WebInputMethodControllerImpl::GetSelectionOffsets    2663 (4.65%)    0 (0.00%)       content_shell.exe
| - SkCanonicalizePaint::SkCanonicalizePaint    2491 (4.35%)    204 (0.36%)     content_shell.exe
| - decompose_current_character 2276 (3.97%)    410 (0.72%)     content_shell.exe
| - SkDraw::ShouldDrawTextAsPaths       2267 (3.96%)    330 (0.58%)     content_shell.exe
| - blink::ScriptRunIterator::Fetch     2210 (3.86%)    455 (0.79%)     content_shell.exe
| - blink::RunSegmenter::ConsumeSymbolsIteratorPastLastSplit    2164 (3.78%)    2 (0.00%)       content_shell.exe
| - blink::SymbolsIterator::Consume     2162 (3.77%)    545 (0.95%)     content_shell.exe
| - hb_font_get_nominal_glyph_trampoline        1842 (3.21%)    149 (0.26%)     content_shell.exe
| - SkScalerContext::MakeRecAndEffects  1833 (3.20%)    1427 (2.49%)    content_shell.exe
| - SkStrikeCache::findOrCreateStrikeExclusive  1784 (3.11%)    241 (0.42%)     content_shell.exe
| - SkScalerContext::AutoDescriptorGivenRecAndEffects   1735 (3.03%)    525 (0.92%)     content_shell.exe
| - ?DefaultSnapshotBlob@Snapshot@internal@v8@@SAPEBVStartupData@3@XZ        1735 (3.03%)    0 (0.00%)       content_shell.exe
| - blink::HarfBuzzGetGlyph     1693 (2.95%)    274 (0.48%)     content_shell.exe
| - blink::ICUScriptData::GetScripts    1687 (2.94%)    370 (0.65%)     content_shell.exe
| - v8::internal::`anonymous namespace'::HandleApiCallHelper<0> 1651 (2.88%)    0 (0.00%)       content_shell.exe
| - v8::internal::FunctionCallbackArguments::Call       1651 (2.88%)    0 (0.00%)       content_shell.exe
| - v8::internal::Builtins::InvokeApiFunction   1640 (2.86%)    0 (0.00%)       content_shell.exe
| - v8::internal::LoadIC::Load  1633 (2.85%)    0 (0.00%)       content_shell.exe
| - v8::internal::Runtime_LoadIC_Miss   1633 (2.85%)    0 (0.00%)       content_shell.exe
| - v8::internal::Object::GetProperty   1631 (2.85%)    0 (0.00%)       content_shell.exe
| - v8::internal::Object::GetPropertyWithAccessor       1631 (2.85%)    0 (0.00%)       content_shell.exe
| - blink::Element::scrollHeight        1622 (2.83%)    0 (0.00%)       content_shell.exe
| - blink::V8Element::scrollHeightAttributeGetterCallback       1622 (2.83%)    0 (0.00%)       content_shell.exe
| - SkPaint::TooBigToUseCache   1618 (2.82%)    403 (0.70%)     content_shell.exe
| - blink::SimpleFontData::BoundsForGlyphs      1544 (2.69%)    216 (0.38%)     content_shell.exe
| - hb_ot_layout_substitute_start       1531 (2.67%)    1529 (2.67%)    content_shell.exe
| - SkStrikeCache::findStrikeExclusive  1493 (2.61%)    1466 (2.56%)    content_shell.exe
| - blink::SymbolsIterator::FontFallbackPriorityForCharacter    1404 (2.45%)    180 (0.31%)     content_shell.exe
| - hb_font_get_glyph   1367 (2.39%)    100 (0.17%)     content_shell.exe
| - blink::WebLocalFrameImpl::RangeAsText       1354 (2.36%)    0 (0.00%)       content_shell.exe
| - blink::PlainTextRange::CreateRangeFor       1345 (2.35%)    7 (0.01%)       content_shell.exe
| - blink::PlainTextRange::CreateRange  1345 (2.35%)    0 (0.00%)       content_shell.exe
| - blink::WebRange::CreateEphemeralRange       1345 (2.35%)    0 (0.00%)       content_shell.exe
| - __security_check_cookie     1319 (2.30%)    1319 (2.30%)    content_shell.exe
| - hb_ot_get_nominal_glyph     1267 (2.21%)    79 (0.14%)      content_shell.exe
| - __scrt_common_main_seh      1228 (2.14%)    0 (0.00%)       content_shell.exe
| - wWinMain    1223 (2.13%)    0 (0.00%)       content_shell.exe
| - content::ContentMain        1221 (2.13%)    0 (0.00%)       content_shell.exe
| - service_manager::Main       1221 (2.13%)    0 (0.00%)       content_shell.exe
| - content::ContentMainRunnerImpl::Run 1195 (2.09%)    0 (0.00%)       content_shell.exe
| - OT::CmapSubtableFormat4::accelerator_t::get_glyph_func      1188 (2.07%)    1188 (2.07%)    content_shell.exe
| - content::RunBrowserProcessMain      1185 (2.07%)    0 (0.00%)       content_shell.exe
| - content::ShellMainDelegate::RunProcess      1185 (2.07%)    0 (0.00%)       content_shell.exe
| - ShellBrowserMain    1185 (2.07%)    0 (0.00%)       content_shell.exe
| - sk_getAdvance_glyph_next    944 (1.65%)     69 (0.12%)      content_shell.exe
| - blink::SkiaTextMetrics::GetSkiaBoundsForGlyphs      928 (1.62%)     16 (0.03%)      content_shell.exe
| - SkStrikeCache::ExclusiveStrikePtr::~ExclusiveStrikePtr      921 (1.61%)     610 (1.06%)     content_shell.exe
| - content::MainThreadEventQueue::DispatchRafAlignedInput      909 (1.59%)     0 (0.00%)       content_shell.exe
| - content::RenderWidget::BeginMainFrame       909 (1.59%)     0 (0.00%)       content_shell.exe
| - SkGlyphCache::getGlyphIDAdvance     875 (1.53%)     875 (1.53%)     content_shell.exe
| - base::MessagePumpForIO::DoRunLoop   868 (1.51%)     1 (0.00%)       content_shell.exe
| - content::BrowserMainLoop::MainMessageLoopRun        867 (1.51%)     0 (0.00%)       content_shell.exe
| - content::BrowserMainLoop::RunMainMessageLoopParts   867 (1.51%)     0 (0.00%)       content_shell.exe
| - content::BrowserMainRunnerImpl::Run 867 (1.51%)     0 (0.00%)       content_shell.exe
| - u_getUnicodeProperties_62   834 (1.46%)     833 (1.45%)     content_shell.exe
| - defaultContains     766 (1.34%)     316 (0.55%)     content_shell.exe
| - WTF::Vector<mojo::ScopedHandleBase<mojo::MessagePipeHandle>,0,WTF::PartitionAllocator>::at  686 (1.20%)     499 (0.87%)     content_shell.exe
| - blink::LayoutBlockFlow::CreateLineBoxesFromBidiRuns 670 (1.17%)     6 (0.01%)       content_shell.exe
| - _hb_glyph_info_set_unicode_props    659 (1.15%)     192 (0.34%)     content_shell.exe
| - base::MessagePumpDefault::Run       594 (1.04%)     1 (0.00%)       content_shell.exe
| - sk_getMetrics_glyph_next    553 (0.97%)     78 (0.14%)      content_shell.exe
| - SkStrikeCache::getCachePointSizeLimit       528 (0.92%)     528 (0.92%)     content_shell.exe
| - mojo::SimpleWatcher::OnHandleReady  526 (0.92%)     6 (0.01%)       content_shell.exe
| - mojo::Connector::ReadAllAvailableMessages   513 (0.90%)     2 (0.00%)       content_shell.exe
| - SkBinaryWriteBuffer::SkBinaryWriteBuffer    511 (0.89%)     511 (0.89%)     content_shell.exe
| - mojo::Connector::ReadSingleMessage  502 (0.88%)     5 (0.01%)       content_shell.exe
| - blink::ScriptRunIterator::MergeSets 493 (0.86%)     286 (0.50%)     content_shell.exe
| - WTF::Vector<mojo::InlinedStructPtr<blink::mojom::blink::SpellCheckSuggestion>,0,WTF::PartitionAllocator>::at        480 (0.84%)     395 (0.69%)     content_shell.exe
| - SkGlyphCache::getGlyphIDMetrics     475 (0.83%)     44 (0.08%)      content_shell.exe
| - WTF::Vector<mojo::InlinedStructPtr<device::mojom::blink::UsbEndpointInfo>,0,WTF::PartitionAllocator>::at    470 (0.82%)     364 (0.64%)     content_shell.exe
| - blink::CaseMappingHarfBuzzBufferFiller::CaseMappingHarfBuzzBufferFiller     468 (0.82%)     13 (0.02%)      content_shell.exe
| - hb_icu_unicode_general_category     467 (0.82%)     188 (0.33%)     content_shell.exe
| - hb_buffer_add_utf16 455 (0.79%)     75 (0.13%)      content_shell.exe
| - blink::Character::IsEmojiEmojiDefault       449 (0.78%)     55 (0.10%)      content_shell.exe
| - SkGlyphCache::lookupByPackedGlyphID 432 (0.75%)     430 (0.75%)     content_shell.exe
| - uscript_getScriptExtensions_62      420 (0.73%)     158 (0.28%)     content_shell.exe
| - blink::ShapeCache::Add      420 (0.73%)     43 (0.08%)      content_shell.exe
| - content::BrowserProcessSubThread::IOThreadRun       391 (0.68%)     0 (0.00%)       content_shell.exe
| - gpu::GpuChannel::HandleMessageHelper        379 (0.66%)     0 (0.00%)       content_shell.exe
| - SkMatrix::setConcat 373 (0.65%)     373 (0.65%)     content_shell.exe
| - blink::ShapeCache::AddSlowCase      367 (0.64%)     79 (0.14%)      content_shell.exe
| - WTF::Vector<UScriptCode,20,WTF::PartitionAllocator>::resize 363 (0.63%)     187 (0.33%)     content_shell.exe
| - base::internal::SchedulerWorker::RunWorker  359 (0.63%)     0 (0.00%)       content_shell.exe
| - memset      357 (0.62%)     314 (0.55%)     content_shell.exe
| - hb_ot_map_t::position       356 (0.62%)     10 (0.02%)      content_shell.exe
| - base::internal::TaskTracker::RunAndPopNextTask      356 (0.62%)     0 (0.00%)       content_shell.exe
| - base::internal::TaskTracker::RunOrSkipTask  356 (0.62%)     0 (0.00%)       content_shell.exe
| - blink::FontGlobalContext::Get       352 (0.61%)     132 (0.23%)     content_shell.exe
| - blink::Character::IsEmojiTextDefault        347 (0.61%)     81 (0.14%)      content_shell.exe
| - blink::ShapeResultBuffer::GetCharacterRange 347 (0.61%)     3 (0.01%)       content_shell.exe
| - hb_ot_map_t::apply<GPOSProxy>       346 (0.60%)     67 (0.12%)      content_shell.exe
| - blink::ShapeResultBuffer::GetCharacterRangeInternal 344 (0.60%)     19 (0.03%)      content_shell.exe
| - gpu::Scheduler::RunNextTask 336 (0.59%)     0 (0.00%)       content_shell.exe
| - base::internal::SchedulerWorker::RunPooledWorker    335 (0.58%)     0 (0.00%)       content_shell.exe
| - gpu::CommandBufferStub::OnMessageReceived   334 (0.58%)     2 (0.00%)       content_shell.exe
| - gpu::GpuChannel::HandleMessage      334 (0.58%)     0 (0.00%)       content_shell.exe
| - blink::ConstructBidiRunsForLine     329 (0.57%)     2 (0.00%)       content_shell.exe
| - SkBinaryWriteBuffer::~SkBinaryWriteBuffer   327 (0.57%)     327 (0.57%)     content_shell.exe
| - blink::Character::IsEmojiModifierBase       327 (0.57%)     61 (0.11%)      content_shell.exe
| - blink::BidiResolver<blink::InlineIterator,blink::BidiRun,blink::BidiIsolatedRun>::CreateBidiRunsForLine     326 (0.57%)     179 (0.31%)     content_shell.exe
| - sse42::hash_fn      323 (0.56%)     323 (0.56%)     content_shell.exe
| - blink::TextRun::NormalizedUTF16     323 (0.56%)     158 (0.28%)     content_shell.exe

We should change TextIteratorTextNodeHandler::HandleTextBox() to avoid
str.find(‘\n’, run_start) which take 22.62%.

This is for InputMethodController::TextInputInfo() takes 18.55%

So far it sounds like we've noted it's much slower to type certain things, and to paste large amounts of text.

It's also incredibly slow to **delete** large amounts of text.

Chrome profiler froze for as much as 4.9 minutes before I gave up. It shows all that time being on the keydown event, and inside is just a huge stack of layout events that are all about ~150ms.

This is pretty easy to repro, and the issue is (seemingly) exponentially worse the more text you delete.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

[Empty comment from Monorail migration]

Chromium version 83.0.4103.61 appears to significantly improve the performance.
However, there is still a difference in latency between Chrome and Firefox on lower-end machines. The difference is not as noticeable on higher-end machines.

Track by https://crbug.com/chromium/892513
See https://crbug.com/chromium/1141742 for analysis.

This issue was migrated from crbug.com/chromium/582844?no_tracker_redirect=1

[Multiple monorail components: Blink>Editing, Blink>Layout]
[Monorail blocked-on: crbug.com/chromium/707656]
[Monorail blocking: crbug.com/chromium/698661]
[Monorail mergedwith: crbug.com/chromium/851931]
[Monorail mergedinto: crbug.com/chromium/892513]
[Monorail components added to Component Tags custom field.]