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Issue 780595 link

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Issue metadata

Status: WontFix
Owner: ----
Closed: Nov 2017
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Mac
Pri: 2
Type: Bug-Regression



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Compositing a large Indexed PNG is very slow

Reported by is...@instrumental.com, Nov 1 2017

Issue description

UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36

Steps to reproduce the problem:
1. Load https://jsfiddle.net/LkoqhhLb/
2. Start recording in the Performance tab of Dev Tools
3. Note pinned CPU, low FPS, and lots of compositing

What is the expected behavior?
Image renders quickly; compare to https://jsfiddle.net/t3vm2hg1/1/ which is the exact same example except the image is not indexed

What went wrong?
Recently I started noticing that a web app I work on was getting really slow. After a lot of debugging, a colleague and I narrowed it down to the fact that Chrome was taking a really long time to composite a default image we were displaying while waiting for other images to load. This doesn't happen in Firefox or Chrome. I suspect that this started happening a few Chrome versions back, but can't confirm - it's possible I just hadn't noticed the slowness before.

Did this work before? Yes 

Chrome version: 62.0.3202.75  Channel: stable
OS Version: OS X 10.12.6
Flash Version:
 
Labels: Needs-Bisect Needs-Triage-M62
Whoops, I think I mis-diagnosed this issue and posted too soon.

Looks like what was actually happening is that Chrome doesn't keep 36MP decoded images in memory (24MP seems fine - not sure what the cutoff is, but it's somewhere in between). So when I was trying to render the 36MP image every frame, it had to be decoded first, and of course that is slow.

I think it would be sufficient to have a console warning or something to help developers avoid going down a long rabbit hole... I get why this limit is in place.

Personally I think I've solved it for my use case by switching to SVG, which seems to not have this limitation.
Cc: divya.pa...@techmahindra.com
Labels: -Needs-Bisect Triaged-ET
Status: WontFix (was: Unconfirmed)
As the issue seems to resolved, we are closing the issue as Won't fix

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