Here is a profile with a "40x40" grid size: https://share.firefox.dev/4cImu0M . My machine probably hit some RAM limit in this case.
Bug 1915328 Comment 3 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
You can also look at this demo directly : https://codepen.io/aragakey/pen/gOJYwEq Profile: https://share.firefox.dev/4fUJfkW Every 2 seconds the demo refreshes. During refresh the memory use is high, and it takes longer to refresh compared to pre-regression.
On a slight tangential note, for similar demo the profiler shows that the memcopy and vector stuff as "ion" time. (Shouldn the category be consistent with the profiles in comment #2 and comment #1?) https://codepen.io/yuanchuan/pen/QWQzbzb : https://share.firefox.dev/3X6rsyu / https://share.firefox.dev/3Z4NkwW