Hi, Today I've upgraded the memory on my Mac from 4GB (2x2GB) to 8GB (2x4GB - link) I noticed that after about 20 mins of usage the disk I/O appear to get very slow. Admittedly this is only a guess on my part - but here's what I notice: - Applications that are already loaded respond fast - for example a page loaded on firefox scrolls smoothly - no perceived slowdown). - Anything that needs to do any kind of disk access is painfully slow - for example XCode appears to compile files about 5-10 times slower than normal. - CPU utilization for running applications is too high - for all of them - A VMWare Windows instance I run grounds to a halt - If I restart the machine it works fine for about 20mis and then the problems start again I've no idea why the memory upgrade would cause anything like that. Btw, I run Lion. If you need any kind of diagnostics dump just let me know. Any ideas? Should I reset/clear/delete anything following a memory upgrade? Cheers, Nikos.