Awful performance in Firefox with lots of lines

1

I work with large files with lots of lines (50k+). Firefox chokes on them and becomes unresponsive very quickly. Chromium performs much better.
Try the following on http://codemirror.net/index.html

var s = 'X'
var lines = s;
for(var i = 0; i<50000; i++){
  lines = lines+'\n'+s
}
editor.setValue('')
console.profile()
editor.setValue(lines)
console.profileEnd()

Firefox takes more than 10 seconds, Chromium does it in a few ms.
It seems to be the calculation of the longest line that takes ages on Firefox. I wonder why that’s the case and if I can do anything about it.

Cheers,
Jochen

2

I’m seeing this take 50ms in Chrome, and 230ms in Firefox 31. I wouldn’t call that awful (50k lines is quite a lot). When I look at the profile, the time seems mostly spent on allocating Line objects, which isn’t too surprising. Which Firefox version were you testing with?

3

I’m using Iceweasel 31.2.
Apparently it is Firebug that makes it take so long, if I remove the profiling, things are much faster. I thought, Firebug would be able to track the net times, sorry.

4

No problem. I’ve let Firebug confuse me like that too. (And have stopped using it entirely, mostly because of such shenigans.)

1 Like
5

What do you use for profiling? Firefox’s internal developer tools don’t seem to be able to do that and I can’t really get used to them anyway after having used Firebug for many years.

6

Chrome, mostly. But FF’s built-in devtools are also getting quite good – they take some getting used to, but the functionality is all there.