Performing a review is very slow in IE 7/8

Performing a review - such as adding comments or changing the view preferences - is very slow in IE 7.

For example:
1) Load https://atlaseye-qa.atlassian.com/atlaseye/cru/CR-JRA-159
2) Click on "TestAdminMenu.java" (the last entry in the tree on the left)
3) Click Prefs->Side By Side View.
4) Wait 30 seconds for the UI to respond and the page to reload.

Every action - including adding comments, changing preferences, and deleting comments - takes 3-4 times longer in IE than in Firefox. During longer waits, IE does not respond to any input and appears to have hung.

The QA server is slow but not slow enough to justify this - UI responsiveness on Firefox using the same server is reasonable. On IE 7 it is almost unusable.