Performance when same tree is loaded in different pages

I have a weird behaviour on FF 3.6 (*): the tree is pretty slow even when I collapse/expand a branch (it is a large tree, around 900 nodes), I can see the CPU of my desktop going to a peak for 5-7 secs

My application has a full header (on an iFrame) with images and links plus a content area (another iFrame with many multiple nested DIVs).
If I only open the iFrame with the tree I dont have the same behaviour, performances are good.

Could the performance of the tree be affected by the structure of the html page or other layout/css properties? Or the number of nested DIVs?

Tnx in advance

Beppe

(*) Chrome works fine, so it is definitely an issue with the browser performance, I am only trying to figure out how to make FF work better (and it does in the case explained above)

Could the performance of the tree be affected by the structure of the html page or other layout/css properties? Or the number of nested DIVs?

The tree performance can not be affected the structure of the html page. Could you provide a demo that allows to recreate the problem ?