IE 8 throws slow running script message when creating issue

With a JIRA instance having around 1000 project and 1500 issue types, when using the shortcut "+ Create Issue" next to the "Quick search", it will throw a slow running script message box (refer the screenshot file Screen Shot 2012-06-26 at 2.54.39 PM.png).

If click on yes, the create issue drop down menu will appear but with empty project list.
If click on no, the same message box will appear 5 times then nothing happen.