Update: My logs were filling up with CPU temp warnings. Cracked the case and found that the the old P4 CPU heat sink was completely clogged with lint causing temps over 75deg C. Some judicious vacuuming and shortly after the CPU temp was in the mid 50's. Performance of my VM's was back to where I remembered it. So in short the culprit wasn't a new OS or VM software but lack of maintenance. Clean your heat sinks and fans!

I don't know if anyone else has seen this but I've noticed my VM's have been performing at the speed of porridge in the unsupported install of VMWare 2.0.1 Server and now VirtualBox too.

Admittedly my machine is ancient (x32 Intel(R) Pentium(R) 4 CPU 3.00GHz), and only has 2GB of RAM but on previous installs of Ubuntu the performance was acceptable.

I didn't pursue the cause of the VMWare slowness to any great extent.

I've now tried VirtualBox. Installing the VirtualBox guest tools into a Windows XP guest took hours. Installing the RT kernel as suggested on some forums still left me with a painfully slow VM. I'm also noticing the host is running the VirtualBox process at greater than 100% (which I didn't think was possible).

The frustration I find with the above scenario's is the waste of time that occurs at each new version of Ubuntu. There is a raft of bugs and regressions to overcome/work-a-round. Hours spent combing forums and wading through cries for help, well meaning, but misguided assistance. Trying to find the needle in the haystack which could be the possible fix... Sigh!.

It's like climbing to the end of every branch on an apple tree looking for a specific piece of fruit. Arrrggh.

So my answer to the above is I need a new x64 bit machine with VT enabled processors. Even if things are slow they'll do it faster:).