add new comment slow

hi,
im running wordpress 3 on rackspace. everything seems fine performance wise. the only problem im having is when im trying to add a new comment it takes about 1 min until its saved and the page reloads.
does anyone have an idea what/where the problem might be?

i’ve already tried to use the same php.ini as on my local (everything works perfectly fine on my local)

thanks

pete