For me that has not happened for a long time. Maybe I need to leave it longer before I bother to upgrade..?
Indeed, I only upgrade when I get more than double CPU performance:
386sx25 -> P60@66 -> P150@187 -> 300A@464 -> [email protected] -> [email protected] -> [email protected].
The i5-2500k @ ~4.5GHz is the first chip I'm considering as a next step, but probably won't bother 'til the autumn when they'll be something a little better.