IE8 latency hanging-up on mouse and scrolling events

Very strange behavior only occurring with IE8 on Vista Premium with all of
the blah blah SP and blah blah and so on for the record. No other browsers
or applications hang momentarily when attempting to scroll a page using
scrollbars or the wheel on a Microsoft mouse; only IE8. Very disrturbing.

This seems to have just started occurring after the last visit to Windows
Update when I allowed update to install Office Live add-in 1.4, NEtwork
Monitor 3.3 and the latest Defenition for Windows Defender.

I will start disabling IE8 add-ins to troubleshoot but any other ideas are
appreciated...