There is also a great feature too when you double click on the little CPU meter down the bottom a large window pops up and shows every plugin and every resource being used and a little bar graph against every one. Often it is only one or two things that can be chewing things up. Rendering these things out is super fast in Studio One.
When converting midi parts with virtual instruments to audio as well there are options there that allow you to go back at anytime after a complete render. Virtual instruments are rendered out to audio, the midi file is set aside and muted. But later with one click you can instantly go back to the Midi file with the virtual instrument again in order to edit the music etc..
Mai Tai can be a resource hog but doing simple things like simply altering the ADSR settings so that less voices are overlapping will greatly reduce the amount of CPU it uses. Choosing your voicing carefully as well really helps. You don't need 6 voices for example to state a minor 9 chord either. You can state virtually any chord with a bass note and 3 voices. It sounds better too.
There are also Mai Tai quality options too which often will sound identical but use less CPU.