Ok...here's what I've found about Zeta 2.1 as a VSTi in X2 under Win 8...

Certain patches will LITERALLY eat the CPU...

Most patches are ok...but on a certain few..on my Quad Core System...the first CPU goes straight into the red...and the 
Audio Engine drops out immediately.

The MAIN offender patch being "Alpha Centauri 1"  When I hold a note in this patch the #1 CPU goes straight to RED..and causes the Audio Engine to drop out...and when I restart the Audio Engine the sound briefly continues to play.
There are others...and I will have to go back through them to find the others...

Anyone else experience this with any of the patches?  It happens when Zeta 2.1 is used  as a VSTi in X2 under Win 8 as a...not as a stand alone.

I'm not a synth guy, so everything is set to default settings.  ASIO and MIDI are set to my Quad Capture and my LPK 25 and 
everything works fine in about 95 percent of the patches.
Specs are in Signature....Windows 8 Pro...Win 8 Quad-Capture driver.

It probably doesn't really help, but, yeah, Zeta can really tax your CPU, especially w/ long sequences w/ lots of filtering and all. I've just tried that particular patch on my MacBook Pro, and one of the CPU instantly jumped in the red.

Granted, I'm on an older machine, but, still, Zeta is one the most CPU hungry synth I have. 

Notice that you have the option to change the quality (Options - Realtime Quality). 

Thanx for the confirmation Rain...

I thought it was quite odd that a patch would do that...
while most don't even tax the CPU above 25 percent...which is still
too much..

But I'm glad to know I'm not alone on this...