Yup same for me here too. Thing is when I look at top, there is next to nothing being used, however the entire physical RAM has been committed (somewhere) and mysql is running from swap. The numbers in top just don't add up.
When it goes bad, I see a huge amount of swap data appearing in /tmp.
I think somebody further up the thread suggested the VPS may be oversubscribed. I can only assume this is the case and I've raised a support ticket with them.
FireBee, Falcon -Soundpool case: CT63@95Mhz + 14MB/512MB + 16GB SSD + FPU + Phantom 25/50 + SuperVidel + SoundPool FDI + FA8 + ADAT + Eiffel, TT030: 4MB/16MB + Crazy Dots, Mega"SST" 12, STbook, STacy 2, MegaSTE, STE: Desktopper case, IDE interface, UltraSatan (8GB + 512Mb) + HXC floppy emulator. Plus some STE's/STFM's