Found a weird performance issue related to XAMPP. Sorry if its off topic but may be of interest to someone. Feel free to move it if necessary - I may also post on the Drupal forum.

On my development box I use XAMPP to install and configure mysql, apache and php. My box runs Windows XP (can't get Ubuntu to reliably recognise my wifi card) and I noticed that whenever I started apache and mysql from the XAMPP control panel the hard drive was almost constantly active. I blamed apache for this and spent a good few hours over a several week period trying to find out why. Only then did I check the system monitor (yes, I know I'm an idiot) and found a program called pv.exe was using 15-20% CPU and a fair bit of RAM.

Googled pv.exe and found it is an event logging programme used by XAMPP that seems to be triggering at 1 second intervals. However, turns out it is only launched if you use the XAMPP control panel. Launch XAMPP from the command line, or use xampp_start application, then pv.exe is not started and Drupal/UC run much better.

Hope this helps someone in the future.

Over and out

Jez