No.
If talking about memory usage it is Xms. That’s the heap mem Java pre-allocates on start and where it puts the compiled rules. If it’s too small (like the default is), rules need to be compiled on subsequent executions, too, which causes lags.
Xmx is important, too. If OH ever requests more mem than that, Java will crash.
However the vast majority of users runs the default (256M on ARM !) without problems, in openHABian I raised it to 350 but you have 650 already. No need to increase further.
In fact doing so is harmful. Not due to garbage collection as you write. But it creates more paging to SD card so thatt wears out faster.
But we’re getting off-topic. Any next discussion please in appropriate threads not here.