Another thing I'd like to remind here: 1,5GHz work fine (even with full load) with the EVM and the iGEPV5 board.
I haven't tested the Letux kernel on the EVM for a while, but I should do that as well.
As far as I know, PyraOS is using your kernel, so anyone in IRC using the EVM is using that kernel without any issues. (and they compile on that and do x86-emulation at 1,5GHz, so they really make use of that CPU).