I total understand your misgivings on their responsiveness...
I suspected that this was due in part to smart select. So for my curiosity and interest of helping...
With a backup of my VM safely tucked away I, decided to plunge into 5160 again to see if changes I did to VM setup in 4560 and the use of a cool utility that goes thru on the Mac and recaptures the default file associations
(go to this thread
http://forum.parallels.com/thread16924.html and run script created by brkirch)
This time I turned security to high and made sure all the shared and smart selects where unchecked.
In Preparing to upgrade to 5160 do the following...
0. MAKE A BACKUP OF YOUR VM PRIOR TO UPGRADING!!!!!
1. While in build prior to upgrade, go to applications and reset default files associations
2. Turn off all smart select
2. Turn off all shared applications
3. set security to high
4. shut down all unnecessary Mac Application before upgrading (especially the ones that were previously associated to Windows)
5. Install Upgrade.
Notes after re-upgrade to 5160
1. Even though i have shared applications turned off in VM setup, when i started the Windows VM it populated the Parallels shared Application folder with all my Mac Applications, like I said, even with them off on setup and grayed out in top application menu. but they seem to be benign.
2. Apparently when i upgraded the first time, the prior versions File Associations, from build 4560 really caused havoc, so clear them out the best you can.
So, Im back in 5160 and this time i didn't have immediate crashing as i did the first time I upgraded that stopped my production work, and conclude that the issue was mainly Smart Select. I have been running stable in 5160 for 2 days now