Logic Pro 7 & earlier Midi latency with virtual instruments only


I am running Logic 5.5 on Windows XP and have significant (probably ~50-100 ms or so) MIDI latency issues when triggering any virtual instrument in Logic Audio). In contrast, there is No latency whatsoever when triggering external MIDI modules with my MIDI keyboard through the logic interface (i.e., by selecting a channel connected to that module) Also, if the virtual instrument has a (virtual) keyboard, then when I click that with the mouse there is no MIDI latency.

I know the problem is with some setting in Logic because when I use exactly the same virtual instruments in Acid Pro, I get no MIDI latency issues using the same keyboard.

Does anyone have any ideas on what the issue might be with Logic? What are the optimal settings to reduce latency issues for virtual instruments?

Would appreciate any help.


My setup:
Dell P4 2.4 GHZ CPU, 4G RAM, Windows XP Pro SP2
Logic Audio 5.5
Miditerminal 4140
KMX MIDI Central
Various External synth Modules: Roland MT32, TX816, Proformance 1 Piano module,
Alesis nano bass, Korg M3R)
Yamaha KX76 Keyboard