Time for some Enlightenment.
I used to think that once a program was running, the window manager was out of the way and the program did it's thing. Working with slow hardware cured me of that naiveness. The window manager really does have a large effect, especially making the difference between a smooth running or stuttering video playback. I choose video playback because it is the most resource intensive visible usage of a computer. Just to recap the laptop is a P3 500Mhz with 256Mb of ram.
Still, in the interests of efficiency I eventually settled on XFCE as my desktop environment to give me a balance of eye candy and resource efficiency. It did everything quite well and I had no trouble watching videos. Until I tried playing some high resolution matroska video files. I knew that these files would push the computer to the limits but I did want to watch my Star Trek.
The poor little thing started to act like someone had shoved a whole hard boiled egg in it's mouth. So I decided to break away from the, what Linux detractors call, windows 95 look and give Enlightenment another try.