When I watch the processes in the task manager it's unclear what part is spiking because as it slows down the numbers also freeze. All i can see is that the cpu usage at the bottom reads 100% just after the spike happens.
The CPU does have Hyperthreading, and I tried turning it off in the BIOS, and it partly helped. So far it seems that I can now listen to music without any juddering, however it does slow down alot if I open another window, and is predictably much slower on other applications like games (not that I was able to play them before, but they seem a good test to see how frequently the CPU slows down".
So thanks for letting me listen to music. Any more suggestions?