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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.
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?
All Replies (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.