[Jach]

Most problems with GC are when most GC implementations introduce non-deterministic latencies, but it can also be because they demand a large heap size to work well. Even if you can swap the GC implementation or turn it off, can you guarantee that when you turn it on, it will only run for < X milliseconds and then stop/allow you to control it again? If you can't, turning it off only buys you a little, unless your language also supports direct [de]allocation. Nim's strategy with GC with plain access to alloc() is pretty nice.