$ time make -j8
real 0m41.105s
user 1m55.404s
sys 1m49.693s
real 0m41.105s
user 1m55.404s
sys 1m49.693s
But the surprising bit is:
$ time make -j6
real 0m37.042s
user 1m52.107s
sys 1m41.501s
real 0m37.042s
user 1m52.107s
sys 1m41.501s
This was with subversion 1.3 after a minor header tweak.