Emulation involves a lot of large byte arrays and static structs that your code updates a lot to represent the hardware. It isn't necessarily creating a ton of objects all the time. I do not have specifics on hand for these emulators but it's not hard to imagine that they could well be running the GC for a few microseconds every few minutes or something [1]. It is a very different type of program than a traditional game, or, indeed, almost any other kind of program.
There does seem to be this odd semi-subconscious idea in the "GCs aren't appropriate for any high-performance" world that they intrinsically work by stopping the world for 50ms several times per second or something, but that does not have to be the case.
[1]: I actually have a number of servers in Go that run on about this schedule. If you eliminated 100% of my GC cost for these servers, I wouldn't care at all, or even notice.
There does seem to be this odd semi-subconscious idea in the "GCs aren't appropriate for any high-performance" world that they intrinsically work by stopping the world for 50ms several times per second or something, but that does not have to be the case.
[1]: I actually have a number of servers in Go that run on about this schedule. If you eliminated 100% of my GC cost for these servers, I wouldn't care at all, or even notice.