Maybe I'm just stupid but shouldn't you be able to get the same hashrate on all or reasonably close to each other?
Indeed. The hashrate is completely dependant on the crypto algorithm being mined, and each algo produce completely different results in speed, some you see measured in hash per second, while others in kilo or mega hash per second.
Currently CPU mining is unprofitable or nearly useless. Perhaps with the likes of monero you could earn 1¢ or something in a month. GPU mining is a tiny little bit better but generally useless at this point in time.
It is absolutely worthless for Bitcoin, and you posted this message in the wrong section, and should move it into
Mining (Altcoins). This area is for discussion about Bitcoin, this is a Bitcoin forum and anything not bitcoin goes into Altcoin or its sub forums.