Why is firefox slow to load a heavy JS file?
I'm trying to troubleshoot some poor firefox performance. The following page:
is extremely slow to load in firefox (tested on linux and mac, firefox 64.0), pegging one of the firefox child processes at 99% cpu for several seconds. The same page loads quickly in both chrome and webkit. The cause, I suspect, is some relatively heavy js (about 45 MB). It's not the transfer of the JS, since this happens when even once the JS is cached.
So, sub-questions:
A. Why is this happening? B. Can it be fixed? If so, how? C. If this isn't the right forum, is there a better place to ask?
Alla svar (3)
45MB sounds like a lot of code.
I don't know whether this tool is useful: https://developer.mozilla.org/docs/Tools/Performance
You can get help from the developer tools team here: https://discourse.mozilla.org/c/devtools
More generally, see: Where to go for developer support
Thanks, that is helpful. Profiling reveals that about 90% of the load time involves "Idle" - image attached. That's a clue, at least. Is this in the vicinity of a known issue with Firefox 64.0?
This application loads quickly in other browsers, and has loaded quickly on previous versions of Firefox.
Sorry, I don't know the significance of those categories. I would refer you to the documentation and forums I mentioned before.