varnish increased the load

[Releaselog | RLSLOG.net]

hey,
I have a dedicated server running Fedora 6 and hosting a Wordpress based 
website with ~80 000 daily unique visitors, already using Wp-Cache plugin 
and eAccelerator. The load was increasing lately a lot because of growing 
number of visitors so I decided to try Varnish as it looks way more powerful 
than Squid and other alternatives. Installation went fine, all is running 
now, but the server load *increased* instead of decreasing. I didn't change 
any configuration, all is set to default (also because of lack of the 
documentation), but as I said, the server load increased at least twice. Do 
you have any idea what could be wrong and what should I check.

thanks

Martin