There is no link with the number of lines.
You get crashes with less than 20 lines displayed ?
People also said that in IE it is loading extremely slow.
Yes, up to IE8 it is a mess. IE9 does better.
I think that at some point you have started to use some features that Firefox not supporting - this is where problem started.
No specific feature is used. Moreover, I never could produce your issue using Firefox on my side.I will not be able to fix an issue I can not produce. That's why I requested the list of extensions you use, to try and reproduce and have a clue. But now you tell me you produce the issue without any extension, I don't know how I can help you.
Devs use Dojo framework to get cross-browser compatibility. I just checked Dojo site : new version ( V1.8 ) has been deployed. I will check changelogs to see if some fixing may concern your issue, and I plan to deploy this new version with V2.5, but there is no clue it can help on this issue.
Is there other users who have the same problems?
I'd also be glad to have users feedback . Please post you freedback here, and any clue on production of the issue will help solve it.may be reason that we have something not up to date on our server?
I don't think issue is on server side (but I may be wrong), I guess it is on browser side.