Hey, thanks for the feedback. There are some specific components that are CPU-hungry, namely the Ambience control - set it to zero and see if it helps. Also reduce oversampling (4x is enough most of the time). There are some cases when the Speaker Sim and Spring Reverb could cause CPU spikes, we are currently discussing it in the support thread: http://www.kvraudio.com/forum/viewtopic.php?t=417324.
I like it too. I compared the cab sim section to Nadir+Kalthallen IR trying to replace the cab sim section with something else. Altough some alternatives came up I find that the original sound really stand its own. Great set and forget tone.