Thom, are you referring to the slowness issue in general, or specifically to "mythcommflag"? Or is it "mythcommflag" causing the slowness in the first place?
If "mythcommflag" is going mental when you go into KDE desktop, will it also happen when selecting something that opens in a browser from the computing menu? I didn't check this.
It's only for marking adverts/commercials isn't it? Can it safely be killed?