Massive CPU Problems


I have massive cpu-problems. I tried to solve this prob the whole morning, but nothing helped. I tried 1.261 and 1.25 no effect. When I play the demo songs, they all crash when achieving a higher amount of tracks. The track-display and the sound itself jolts very heavy, so that a serious work with renoise is impossible. Also very heavy disturbing sounds appear all the time. This increases when deminish the outlatency value (default 100, 300 crashes as well). Btw. even if I put this value to “5” i can not record notes in the right measure when pressing notes on the keyboard during record mode.
My system is:
P3 700, >300 MB ram, Nvidia Geforce2, Soundblaster PCI
I looked up the log.txt, there are no errors. I checked and replaced the nvidia drivers as they may cause problems, to 40.03, 28.35 and standard.
I tried different versions of renoise (1.25, 1.261). No effect.

What can i do? Help!