> Try using an older stacking WM. It is shocking how fast they are and how few resources they use. Their problem is that they're not maintained.

Window Maker is still maintained, it even gets new features now and then :-).

That's what I am using, with a few dockapps, including one for the system tray. It works fine even with modern apps.

And since GP mentioned NeXT, it should be the perfect match. Window Maker is based on the NeXT UI.