GSX is dependent on the Host OS (linux or Windows) so you have all that overhead to deal with. ESX is a very barebones os that remaps hardware to the virutal servers, this takes up ALOT less overhead and results in better performance.
I wouldn't be so quick to blame GSX for your printer issues. I used to work for MS and supported printing. If you are seeing CPU monopolization by Spoolsv when printing, then you could be looking at a problem with a 3rd party port monitor or version 2 driver (kernel mode driver). Optimally, I would do a perfmon log of the Process and Thread objects and get a userdump of the offending process when the CPU is being monopolized. With that, you can find what thread is causing the problem and get it's thread ID. With the tread ID number, you can track it down in the user dump and nail down the root cause...
Since most people don't know how to use a debugger, I tell them to look and see if their printers are using version 2 printer driver or a 3rd party port monitor. I recommend upgrading any version 2 driver to version 3 (user mode driver) and removing any 3rd party port monitor.
However, as stated in earlier postings, GSX was never intended for production environments, ESX is.
Microsoft Certified Nut.