7507 - Performance slow after upgrade

Upgraded two weeks ago to 7011 to 7507. Since the upgrade I am receiving multiple complaints daily about slowness and system hangs.

Here's the system config.

Windows 2003 Server R2

SQL 2005 Sp3

Quad 2.13 Ghz Xeon Processors

4 GB Ram

30 GB Primary Drive

100 GB SQL Data Drive

Java Heap space 1024MB

What I've observed during periods of slowness:

Issues occurring trying to view or edit Requests.
Local Processor at 90%+ (This occurs most often. Its usually the local processor which is maxed, but never local and server at the same time.)
Server Processors at 90%+ (Happens, but not typically the case)
Ensured latest version of Java installed.
Latest (last) IE7 version installed. (I have users on IE 6 thru 8. No difference.)
Disabled IE Phishing and Pop-up blocker. No Joy
Tried Firefox for grins. (Better performance. Not an option for our company.)

Please assist.