on my in-order execution machines, yeah, KDE4 isn't all that snappy. on my out-of-order execution machines, it's fine. A speed-demon? no. Significantly less of an abomination that Firefox 3? yes. A small set backwards from 3.5.9? also yes.

For the record, my current "main rig" is an Athlon XP 2600+ with 1GB of DDR1 with a Geforce 6200 256MB AGP card. So, yeah, it's a little long in the tooth. But I don't see what the big deal is. Are you using a GeForce 7 or 8 series with the 177-series drivers? I hear those cards with those drivers like to seriously but-heads with Kwin and Plasma.