Answering my own questionAfter some more digging: apparently the resource hog was wdaemon (daemon that emulates a drawing tablet so that it can be hotplugged into X). This was a surprise since my new laptop also has the same one installed - and doesn't exhibit the slowdown.
I've emailed the maintainer and asked him to check out the problem.Another service that affected the speed was cpuspeed - but that's only when "performance" was not selected as the current profile.
