I've just built a shiny new i3 system for use as a home server and to host a Minecraft world. The CPU is clocked at 3.1 GHz and I have added 8 GB memory, yet the system is substantially slower than the Atom (clocked at 1.6 GHz) I was using before.
The system is unable to serve files at more than about 200kB/s, takes about ten seconds to format a manual page, and the Minecraft server continuously complains about not being able to advance game time as fast as real time.
Any ideas what might cause such drastic problems? The last time I've seen an effect like this was with uncached memory on an i486. :)