MD5 test slowdown

I'm observing some heavy slowdown seen with md5 test on PowerPC:

1. On the MPC8572 machine with today's HEAD I'm getting:

# md5 -t
MD5 time trial. Digesting 100000 10000-byte blocks ... done
Digest = 766a2bb5d24bddae466c572bcabca3ee
Time = 36.930565 seconds
Speed = 27077842.000000 bytes/second

2. While a couple of months back it yielded 6x shorter times on this  
very same hardware, like this one:

# md5 -t
MD5 time trial. Digesting 100000 10000-byte blocks ... done
Digest = 766a2bb5d24bddae466c572bcabca3ee
Time = 6.027277 seconds
Speed = 165912400.000000 bytes/second

Timers work fine, the slowdown is real. I don't know if this is  
PowerPC related, and was wondering if anybody observed something  
similar on other archs perhaps? Any suggestions what could be causing  
this or where to look? I cannot see immediate suspects in the arch/ 
platform code.

Rafal