Mongrels slower than Webrick??

Hi list,

I've just run my testscript 100 times to see if mongrel really was
that fast as the internet suggested.
Both webrick as mongrel are run in production mode, with the same
tests.
Both are run as a single process and default logging.

But in every test mongrel is a bit slower than WebRick,
for example :

Webrick: AdminController#index 101(count) 0.0457 (Avg) 0.5519
(Std)
Mongrel: AdminController#index 101(count) 0.0536 (Avg) 0.6123
(Std)

It's not much difference, but I suspected Mongrel to be superior to
Webrick.
I'm running both tests on Ubuntu 7.04. Mongrel was installed by gem
install mongrel.

Have I done something wrong?

Joram