If you are user of jgarzik's CPU miner, try also new 'cryptopp_asm32' algorithm. It is working well now and improve performance for many users (hashrate is same or better than in official bitcoin client). Thanks jgarzik!
Yes, changing the algorithm gave me a huge boost:
4way:
HashMeter(0): 16777216 hashes, 291.09 khash/sec
HashMeter(1): 16777216 hashes, 284.03 khash/sec
HashMeter(2): 16777216 hashes, 280.10 khash/sec
HashMeter(3): 16777216 hashes, 278.72 khash/sec
cryptopp:
HashMeter(0): 16777216 hashes, 446.86 khash/sec
HashMeter(1): 16777216 hashes, 434.61 khash/sec
HashMeter(2): 16777216 hashes, 419.85 khash/sec
HashMeter(3): 16777216 hashes, 417.87 khash/sec