Strange as hell. It's definitely DB, but I can't figure out what exactly. Playing manually on a VM works flawlessly even if a couple of VMs are "lagging with DB" nearby.
I tried putting DB "in" the VM completely, tried a fresh install of a DB, tried switching all plugins off, tried generic routine instead of Belphegor. Tried severely limiting pickup and loot radius. Still the spikes are there (the more monsters and objects around - the more spikes it seems). What a bummer =\
PS. Also I upped the clock on my CPU a bit, doesn't help either.