Long time user and lurker. Seen similar reports in the forum so thought I would share my experience in hope that a fix is being worked on
Prompted to update from 4.x last week on Vista 32 bit system, I accepted and did the update. Since then system has slowed considerably. After coming out of sleep mode it takes a very long time for programs to start up. Task manager shows CPU (all 4 cores) at 100 % and a lot of RAM in use. Trying to work or open firefox etc takes forever. Since reading the forum seems like Avast is performing its scan etc. I permanently disable AVAST and try returning from sleep again and system runs normally, no waits.
Even after re-enabling avast, system tends to run slower, especially email and browsing. Its not as fast as 4.x was. Uninstall and reinstall, clean etc has not helped either
I have a gateway FSX Q6600, 3 GB RAM , 500 GB HD, 8800GTS video card
On the other hand I also have the same version on my laptop running windows 7 64 bit without any problems. Works great
Thanks for reading
Bill