Mac: FXAA/SMAA Severe Performance issue

[canny]

In the latest build, 7.1.12.13550888671 (64bit), enabling FXAA or SMAA divides the performance by 2 on my macbook Pro M2 (it used to have a negligible impact).

https://secondlife.canny.io/admin/board/bug-reports/p/fxaa-smaa-severe-performance-issue-mac-m2

[canny]

This issue has been linked to a Canny post: FXAA/SMAA Severe Performance issue Mac M2 🎉

[AtlasLinden]

I was able to reproduce this on my M1 on Mid+ graphics on both ForeverFPS (7.1.12) and 2025.03 (7.1.13). Although my FPS wasn't halved as the reporter has observed I was bumped from 84 FPS to 60 upon switching the AA setting from Disabled to FXAA (or SMAA).
A smaller performance drop was observed with the same actions on ExtraFPS (7.1.11): ~84FPS to 79.
With graphics set to Ultra on ForeverFPS and setting the AA from Disabled to FXAA, the FPS drops from 36 to 27.
The above tests were performed at region: TextureTest.

Please also see the comments from the reporter in the Canny who has looked further into the possible source of the issue.

[Dan-Linden]

The original reporter, observeur, has done quite a bit more analysis of the issue. Those notes are on the canny issue.