What LT mode does is eliminate the inherent plugin latency that you get when using a DSP card. When you are done tracking simply turn the LT mode off as you don't need it when playing back. Set your project latency to say 128, enable input monitoring and simply enable the LT mode on the 1176LN and now you have zero plugin latency when tracking.

Say you have a 1176LN in the FX bin with your favorite amp sim and you want to record a new track or overdub using the 1176LN in 'All buttons mode' to add a little more bite in combination with your amp sim. Where the LiveTrack mode does come in handy is when you are tracking/overdubbing or want to run a monitor mix and are using UAD-2 plugins at lower latencies. You would only enable those plugins that are affected. You would not use LiveTrack mode when you are in the mixing phase as it is not necessary (with DAW's that have auto PDC), and will only burden your native CPU. I can only get (2) FATSO's running in LT mode crackle free, but adding a third will give the rice crispies as my native CPU is pushing 60%-70% wilth just those three plugins. Thank God for my UAD-2 QUAD, as I can easily run (8) upsampled FATSO's (with tranny enabled) and my total native CPU hit is about 4% 128 samples and still have about 20% DSP left for lot's of less DSP intensive plugins. It kinda makes the WaveArts Tube Saturator look rather CPU light in comparison. With LT mode disabled the native CPU load drops to near zero (about 0.6%) as all the processing is done off the UAD-2 DSP at that point. One stereo instance of the upsampled FATSO (with tranny enabled) uses about 21% of my E8400 (3Ghz) Core 2 Duo when in LT mode 128 samples ASIO. Quite interesting to see how much native CPU a UAD plugin uses. The LiveTrack mode will increase native CPU use as the UAD-2 plugins are essentailly running off your native CPU. Billy Buck are you saying when mixing turn on that mic icon to cut cpu?

Uad plugins manual