This is what I have:
Intel core i7 - 3770 CPU @3.40 GHz, 64 bit OS, 16GB Ram, SONAR X3e Studio. Focusrite 18i20 going into my PC via USB.
I'm using Zero-G's Nostalgia VST with 2 MIDI channels loaded, along with Play that has 7 MIDI channels loaded, EZ Drummer and about 8 channels recorded audio. On playback, I'm getting stuttering from the Nostalgia VST, clicking/dropouts, very brief intervals but enough it's noticeable when I bounce to .wav. I've adjusted the ASIO settings every possible way, minimum to maximum, and the same with MIDI playback buffers, everything from minimum to maximum settings and every combination in between. I've defragged, updated, etc.
Any suggestions of where to go next?