Hey tunes,
Always glad to help another SONAR/UAD user!

I am surprised that UA does not include this tip in their UAD user manual. Other DAW apps like REAPER, also benefit from using the mono (m) UAD versions on mono tracks. As you can see, the DSP savings can be quite substantial. Using the specific mono version of the FATSO on say, a bass track will drop the DSP from 40.5% (w/ tranny enabled) on a single DSP to 25.2%!
Here are a couple of other UAD tips that you may not be aware of:
1) Globally disable/enable UAD plug-ins for when you want to instantly A/B a mix with/without UAD plug-ins: Make sure the UAD meter is open and has focus when you are playing back a project with UAD plug-ins:
Press
Ctrl + 1 (num keys): toggles all UAD-1 plug-ins
Press
Ctrl + 2 (num keys): toggles all UAD-2 plug-ins
2)If you are not using the UAD's own preset management system, then you should be.
Click on the little floppy icon on the bottom left of the UAD toolbar. A drop down menu will appear where you can quickly load/save/copy & paste UAD presets. You can copy and paste presets between like plug-ins. The best part is once you navigate to the preset folder for a UAD plug-in, it will always remember it's location. You do it once for each of your plug-ins and you will never have to go through the laborious process of locating a plug-ins preset folder every time you change to a different plug-in like you are forced to when using the ubiquitous and antiquated VST preset system. I can open any UAD plug-in and with one mouse click I am in it's own unique preset folder.
Cheers,
Billy Buck