[Webkit-unassigned] [Bug 236130] New: Low fps when mesh instances are scaled to 0

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=236130

            Bug ID: 236130
           Summary: Low fps when mesh instances are scaled to 0
           Product: WebKit
           Version: Safari 15
          Hardware: Mac (Intel)
                OS: macOS 12
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: WebGL
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: gbalasis87 at gmail.com
                CC: dino at apple.com, kbr at google.com, kkinnunen at apple.com

I noticed a significant performance drop in WebGL in the latest webkit versions, appearing under these specific circumstances:

- Import a geometry and create several instances of it
- Add the instances under a parent (e.g. a box geometry)
- Scale the parent to 0

This makes the fps drop significantly. Here is a playground from BabylonJS where the issue is replicated:
https://playground.babylonjs.com/#SM5RNH#24

Here is a playground where the issue is not replicated. The difference between this and the previous one is the scaling of the parent. This time it's not zero:
https://playground.babylonjs.com/#SM5RNH#23

I would expect the opposite result - since the scaling is 0 and nothing is rendered, the fps should go up, but on MacBook Pro 2019 it drops from 60fps to 3-5fps.

Here is the forum of BabylonJS where I had initially reported the issue:
https://forum.babylonjs.com/t/framerate-drop-on-ios15-with-scaling-0/25928

The issue can not be replicated on Chrome.

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