<stares at feet and mumbles>erm, 24GB
16GB packs were on offer at Ebuyer, and I thought it might help OK?
Looks like we were running 6 Minecraft servers in that VM, on top of the ZoneEdit, storage, email storage with spam filtering, caching web proxy. . .
Down to just three now, lag is far better.
Have spent part of the evening getting Munin (yes the server runs that too) to monitor the Minecraft VM and user count and lag of one of the servers. The disk latency is pretty bad on that VM, coming in at 250ms despite the underlying host OS showing its RAID1 array that the VMs are on at a steady 15ms. The Minecraft VM only has 10GB out of that ram so there should be plenty of cache on the host.
Bah, it's getting late, I'm grabbing a mug of tea and going to read a book. Perhaps have another look tomorrow.