Perf: changeLineHeights leads to long tasks on a decently sized file

[deepak1556]

Testing #253007

• Install web-tree-sitter npm dependency
• Open tree-sitter.js in build that has PR to test variable font sizes #253000
• See the editor is stuck for a few seconds before it becomes responsive

Does this processing have to be on the critical path ? Can they off-loaded to a worker thread ? Also why are the initial commit calls expensive in this case ?

Trace-20250701T202643.json.zip

[aiday-mar]

Hi thanks for filing this issue. I looked at the commit method. Its complexity is O(n*log(n)) where n is the number of lines with special fonts which were added. In the initial call, I suppose n is a rather large number. Despite this the complexity does not seem to be very big so maybe there is some sort of bug in the code. Perhaps we could offload the computation to a worker thread.

cc @alexdima