Comment by TeMPOraL

Some of the work done to work around GC feels similar to the work you'd do in C/C++ to work around memory fragmentation issues. Also, depending on the language/runtime, you might be able to influence the GC algorithm, or at least the frequency with which it runs. If you can e.g. run a GC every second for not longer than ~1 frame, then pauses won't be noticeable.