conflicts-test very slow over svnserve (Windows)

I haven't looked deeply into it yet, but it seems that the
conflicts-tests (the C tests) are very slow when testing over
svnserve. I noticed this while testing 1.11.0-rc2, but I see the same
with trunk and with 1.10.x.

Running the entire conflicts-test.exe (on a ramdisk):
- ra_local: 23s
- ra_serf: 70s
- ra_svn: 982s (16m22s)

The difference between ra_local and ra_serf strikes me as normal
(after all, the conflict resolver contacts the repository a lot to
fetch information). The time of ra_svn not really :-).

The slowdown seems to be spread over all the tests of conflicts-test
(the dots of the test progress come evenly spread).

Is anyone else seeing this? Only on Windows, or on *nix too?
A performance problem with tree conflict resolution specific to svnserve?

-- 
Johan