Doing a deep equality comparison in RenderBox::updateExclusionShapeOutsideInfoAfterStyleChange will make it so that it does not have to recreate the shape in as many situations.
I think this is a dupe of bug 92164
Created attachment 187942 [details]
Patch to update comment
You're right, it is a dup. Updating the comment in the code to point to bug 92164.
I think it's enough to just mark the bug as dupe. The 3 people who follow the link from the bug can just click through.
*** This bug has been marked as a duplicate of bug 92164 ***