I installed ImageMagick http://www.imagemagick.org
to test basic image processing performance, specifically this ImageMagick command:
convert -resize 900 cloudyearth8k.bmp x.png
...which resizes a 100MB 8192x4096 BMP file (NASA Blue Marble image) down to 900x450 and converts to png format. I believe this is all fixed-point calculation, albeit a lot of it.
For this super-large image the command took about 207 seconds on the plug compared to 170 seconds on a 1.0GHz P4 running Fedora.
Using a smaller source file, cloudyearth2k.bmp (2048x1024), took 18 seconds on the plug vs. 4 seconds on the P4, so more of a relative difference there.
The result from the plug was correct in any case--here's a 512x256 version: