massive slowdown from new scrollbar

[jerch]

Repro:

• run ls -lR /usr in demo
• move mouse off the terminal widget while the output flows

--> massive slowdown with high CPU usage, seems to be caused by tons of setTimeout/clearTimeout calls

[Tyriar]

@jerch timeouts are actually massively inflated in devtools so can't be trusted in a profile. This isn't actually a problem.

Back when we could use the JavaScript profiler tab in devtools this could be verified as all the overhead involved in the performance tab could be removed, but they removed this from Chromium unfortunately.

[Tyriar]

Having said that, we could add some debouncing or something to the onDidScroll event which would make the profiles much less noisy. Ideally I think a single event per task would run a microtask.

[jerch]

@jerch timeouts are actually massively inflated in devtools so can't be trusted in a profile. This isn't actually a problem.

Oh well, wasn't aware that setTimeout/clearTimeout are that toxic in the profiler. Its prolly the same with my other comment here --> #5176 (comment)