Wild guess: switch audio to Single mode. It's not a solution, but a way to hear if FX is audible if all audio is channeled to one output.
Do you have an ASIO driver installed? If not please give it a try. E.g.
http://www.asio4all.com if you do not have an ASIO device driver (beta 2 seems fine).
Will bring your latency likely back to appx 1/4 or less. Again not ment as a solution to the problem. But you never know.
Do you have the latest soundcard driver installed?
If you select an other EQ preset in preferences does it make a change?