Do you already have homing switches installed? If not I believe they are required for Grbl 1.1 and CM4. Homing and setting zero are two different things. Homing tells the machine where it’s at “Machine Position”, zero is whatever you set it to be and stays persistent until you tell it otherwise. Homing only “has to” happen when you turn on your machine/connect to CM, me personally I re-home between each program just to make sure I end up at the same zero before I run the next program (in case steps were lost, belt slipped, etc.).
Example of why homing is important, to me at least:
Home machine, move cutter to zero of my cut, set zero, run part.
Program runs, remove part.
Now say I decide to go inside, eat inner, watch some Netflix, turn machine off. I go back out to the shop a couple hours later, move my machine by hand to change a bit, or whatever reason.
Now I want to run another of the same part, I turn the machine back on, connect to CM. If I now move back to zero, without homing, does it move back to the same place? Not likely unless I moved it back by hand to “exactly” the same place that it went before I shut it down.
With homing I home the machine, then jog it back to zero and it goes to exactly the same place, even if it’s shut down for a week and I’ve moved it all over by hand.
For me I use some dedicated fixtures for work holding, so my zero is usually in the same place, regardless of what I’m cutting. So being able to home, then return to that hard X/Y is critical for using my fixtures.
I can’t say I’ve noticed a difference in running actual programs with CM4/Grbl 1.1, versus running CM3 and Grbl 0.9 as far as smoothness (someone else may be able to answer that better). However jogging is much smoother, and the feed over rides are really nice!