I know it's slow. :-)
:p 'slow' wasn't meant in any devaluing way -- it's unfortunately a factor that adds some variance at higher difficulties and our difficulty is high :/
It's in GUIminer.
I am not familiar with GUIminer and how/if it measures actual hardware device output or also looks only at the found shares rate which might be low when you cannot get any new work from the pool. Anyway: It appears that the only problem is the DDOS attack.