I was able to reproduce.  I did a timeline capture in Chrome devtools. It revealed that TypedArrayBuffer.set is where all the CPU time is being spent.

Renaming issue: bug is unrelated to WebGL. It is a JavaScript related regression.

I think this has been reported before – possibly in the V8 issue tracker – but can't find the bug. V8 folks, can one of you help find it?

Increasing priority to P1 because this is a huge performance regression for a client's app.

"Tried to reproduce the issue on the reported chrome version stable 62.0.3202.94 using windows 10 with the below mwntioned steps.
1. Launched Chrome.
2. started http server.
3. Opened the attached file.
4. Pressed ""go"" after its loaded.
5. Opened console in dev tools.
We searched for 'the parameter 'mc' mentioned in comment#0 to know the performance, but the console page didn't show any such. Attaching the screen cast of the same.

@Reporter: Could you please check the screnn cast and let us know whether we have missed any steps to reproduce the issue.

Thanks!"

Deleted: 786686.mp4 1.8 MB

	786686.mp4 1.8 MB View Download

Parameter "LOAD",it's a parameter from fourth step

Deleted: image.png 452 KB

	image.png 452 KB View Download

Dug up the related bugs.

There seems to have been a significant performance regression in Chrome 62 and this should be investigated ASAP.

I'm sorry for the trouble, this has been my fault. We're working on repairing this regression for the 64 release.

Another related bug: http://b/69608273

The fix or a mitigation should land in 63. Let's decide what to do exactly after the fix landed.

Clarification: initial fix should land asap and than we need to mitigate/fix the situation for >=63

Please land the fix before requesting merge review and make sure to add this bug ID in the CL.

ping!

Sorry for the delay. We've been working on this, but I forgot to include this issue # on CLs (they are all tracked at  https://crbug.com/v8/3590 ).

Just ran the benchmark attached in #0. All x64 Linux release builds, lower is better:

61.0.3163.11: 1556 LOAD
62.0.3202.94: 4392 LOAD
64.0.3280.0:   926 LOAD

From these numbers it looks like the regression has recovered and we've actually improved over 61 by >1.5x.

The CLs that need to be backmerged are, in order:

https://chromium-review.googlesource.com/786414
https://chromium-review.googlesource.com/789010
https://chromium-review.googlesource.com/788857

They're all on the current canary 64.0.3279.0.

Please set to Fixed.

Merges are big but important. Canary looks ok. Please merge this to 63 today.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/f126e6b4cd698e2916b53f705c446efc7b1a5de4

commit f126e6b4cd698e2916b53f705c446efc7b1a5de4
Author: jgruber <jgruber@chromium.org>
Date: Tue Nov 28 13:20:30 2017

Backmerge TypedArray.prototype.set performance improvements

This is a squashed backmerge of the following CLs:

[typedarrays] Reduce overheads of TA.p.set
https://chromium-review.googlesource.com/720661

[typedarrays] Fix a wrong type casting in TA.p.set
https://chromium-review.googlesource.com/732865

[builtins]: Simple port of %TypedArray%.prototype.set() to CSA TFJ.
https://chromium-review.googlesource.com/786414

[typedarray] Add set fast path for JSArray source arguments
https://chromium-review.googlesource.com/789010

[typedarray] Widen set fast path for JSTypedArray source arguments
https://chromium-review.googlesource.com/788857

LOG=N
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true

Bug:  chromium:786686 , chromium:768775 , v8:3590 
Cq-Include-Trybots: master.tryserver.v8:v8_linux_noi18n_rel_ng
Change-Id: Ic1668a1e597c860f306a9e0fa4a73daab5565dba
Reviewed-on: https://chromium-review.googlesource.com/793042
Reviewed-by: Michael Hablich <hablich@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/branch-heads/6.3@{#91}
Cr-Branched-From: 094a7c93dcdcd921de3883ba4674b7e1a0feffbe-refs/heads/6.3.292@{#1}
Cr-Branched-From: 18b8fbb528a8021e04a029e06eafee50b918bce0-refs/heads/master@{#48432}
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[add] https://crrev.com/f126e6b4cd698e2916b53f705c446efc7b1a5de4/test/mjsunit/es6/typedarray-set-bytelength-not-smi.js
[modify] https://crrev.com/f126e6b4cd698e2916b53f705c446efc7b1a5de4/test/mjsunit/es6/typedarray.js
[modify] https://crrev.com/f126e6b4cd698e2916b53f705c446efc7b1a5de4/test/test262/test262.status