OK, this one is strange. I load up a patch from the Horizon Series Concert Guitar in K2 inside a standalone version of VE Pro (32-bit). When I play on a midi keyboard, I get about a 15 second delay (yes, you read that right) between key presses and a sound. Once the sound occurs all the key presses keep coming in time. So it's a fixed delay from the time I press a key to hearing the sound. Note that I see the midi indicator in VE Pro immediately as expected, but no sound until later.
If I click the virtual keyboard in K2 then it works as expected with no perceptable delay. If I set this up in the server and throw midi at it from another program then it works fine also. If I load up sounds from a non-VSL library it works fine from the midi keyboard. If I load up the same patch in K3.5 Player (demo mode) that works fine. Using K2 standalone without VE Pro also works as expected.
It's entirely possible I have something set up incorrectly. I haven't used Horizon and K2 in years, and so I suspect there is some user error. But the data doesn't make any sense to me.
I'm on OS X 10.6.1. K2 version 2.2.4.001