Didn't find Superfetch in services... But found another thing that annoyed me earlier: Windows Media Player Network Sharing Serivce. I've noticed in the Resource Monitor, it uses plenty of CPU-power. Turned it off, but didn't see any significant difference in performance.
But the by far most CPU-power consuming service is the SearchFilterHost.exe, usually it uses 80-90% of the one of my cores, often maxing out on 100% usage. At the same time the other core is working on 40-60%. Has done this for weeks now. So the "normal" CPU-consumption is for the SearchFilterHost alone 47% in average (overall CPU-usage for both cores: 65-75%).
EDIT: Just found the Superfetch-service and disabled it... CPU still running on around 70%.
Solution? Don't know, maybe I shouldn't have upgradet the last time (from 7022 to 7068), but done a clean install? Wait for the RC and new clean install with that? Still don't know, whether this would do the trick - I've seen this 'phenomenon' earlier on other systems, XP as well as Vista, so maybe it's something we have to live with on certain Windows systems?