Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
Can you make the test suite available to the ImageMagick developers. We could just run the test and identify the source(s) of the slow down. If not, post a URL to you detailed results so we can try to determine the source of the slowdown.
Look for 5 or 6 different images of different types (PSD, PDF, EPS, TIFF, etc) that show a large difference in processing time between 6.2.5 and 6.2.8. Add a README.txt file showing the command you use for each file type and the processing time you get in IM 6.2.5 and IM 6.2.8. Post a URL to the files here or send a PM. If we can reproduce the differences in time we will account for the differences and/or fix the reason for the slow down.