How to improve performance un IE

I’m using dhtmlx 2.1 (menu, grid, layout, tabbar, window) in my aplication , but I have a problem.

The performance is better in Firefox than IE.

When I work in IE my aplication is very slow.

What is happening?

How can I correct this?

Thanks for your help.

The IE js engine is more slow than one of FF, it is expected.
If you heavily using dhtmlx layout element you can try to upgrade to dhtmlx 2.5 , in this version layout elements was seriously updated to work faster.