Since updating to 7.5, the local adjustments have substantially increased in performance.
Both CPU and GPU now show higher use than before*. My system: Windows 10, i7-9700k, RTX3070, 32GB RAM. Files are 32MP CR3.
Would be interested in how it runs for @Kyosato (with your Threadripper and RTX4090).
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*CPU all cores peak and GPU up to around 50% when making adjustments and results showing instantly (milliseconds delay).
It works with multiple masks including automasks touched up with the eraser… duplicated, inverted… so far I have not been able to break it with adjustments that don’t make sense from an editing perspective.
I did have to do a clean re-install, as just doing the update like I had previously, resulted in some weird behaviour – Masks could not be hidden on unedited images that had no LA applied before. It did work on images that had local adjustments applied previously. Now the option to show/hide the masks, appears as soon as an adjustment has been made after creating a mask.
Although I had not encountered the issue with any of my photos, images shared by other users that had problems with highlights no longer show these problems for me.