Re: [100 TH] Slush's Pool (mining.bitcoin.cz); TX FEES + UserDiff; ASIC tested

Cluster performance going down
From 440 to 340, why?

Probably because many workers are no longer accounted...

Maybe there was a network problem?

Its now back up to 450

Just a quarter of an hour after the OP (or just two posts thereafter, if you prefer):
https://bitcointalk.org/index.php?topic=1976.msg3876707#msg3876707
It's back for about 30 hours already... :-)