Musicians[0] (electronic and otherwise) do absolutely perform live with real-time AU/VST synths and effects.
There are some constraints on how much complexity a single machine can handle but MIDI sync, Ableton Link etc. allow to combine multiple computers and hardware synths in one setup.
Anecdotally, I don’t perform live but I write music as a hobby and I rarely if ever bounce to audio to free up RAM or CPU. I do bounce for artistic effect though (such as reversing a drum loop or shifting it up/down an octave).
There are some constraints on how much complexity a single machine can handle but MIDI sync, Ableton Link etc. allow to combine multiple computers and hardware synths in one setup.
Anecdotally, I don’t perform live but I write music as a hobby and I rarely if ever bounce to audio to free up RAM or CPU. I do bounce for artistic effect though (such as reversing a drum loop or shifting it up/down an octave).
[0] Like Caribou: https://m.youtube.com/watch?v=8s7Z3vMUGrs