Had this problem with cmucl src/code and src/compiler directories a
while ago but it was fixed.
However, try getting the file list for ansi-tests/ansi-tests and
scroll down a bit. It brings firefox to its knees. Chrome is a bit
better but it still takes a while on my 3GHz imac.
Compare this with github.com/rtoy/ansi-cl-tests. It's very smooth and
takes no time at all.
(It would probably be nice for its own sake if ansi-tests put related
tests into subdirectories instead of all the files in one directory.
But that's a different issue.)
--
Ray