Pro Micro - no just the same.
Teensy 4.1 - Yes it is a much faster processor, so it can get round all those multiplexer and pots more quickly.
The main problem is that you didn't think in advance about how long it would take you to cover all the inputs you need while planning your system.
It is not a memory issue it is that you are trying to do too much.
Your code is a bit turgid. When you find yourself writing the same lines over and over, then there is a much simpler way of doing things. Like the way you setup the mux pins.
It won't affect the performance but is is a poor bit of code.
Remember you only have two hands, and most of the time you will be reading pots and coming up with a no significant change result.