Javascript in IE8 very slow, IE7 + others fast using jQuery, jQuery UI, nyroModal

The page is rendered within an nyroModal (loaded via ajax) and the DOM is manipulated quite a bit using several plugins before actually showing the page.

Everything is fine in non-IE-Browsers and IE7, but in IE8 the resizable and draggable of an div is very slow and crawles along.

I know IE8 is slow. I know my DOM is big. I know i use a lot of plugins. My question is, what exactly slows it down, as other Browsers do it well?

I deactivated every plugin after each other to locate the culprit. Only having resizable activated it is still slow.

I used IE8 profiler and it says offset uses most of the time.

EDIT: I analyzed the page using dynaTrace AJAX Edition and it showes me that these 2 functions are responsible for the most exec time:

jQuery.fn.offset = function(options)

and

jQuery.expr.filters.hidden = function(elem)

both in jquery.js

i read somewhere that IE8 has problems with offset, but how can i circumvent this?

Edit2: I builded a test-page with just a link to open the page with all the resizing in a modal. works ni开发者_如何学编程ce also in ie8 ! so i guess the big DOM of the modal-parent-page is the problem.

any advice appreciated!

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Dynatrace has a very good javascript profiler. Check it out.

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Check that your browser is not running in IE7 emulation mode.