In general when you tune knobs for GC, you pay for benefits in one area with sacrifices in another. Two big knobs to turn are pause latency and throughput. You probably wouldn’t want to go full “optimize for latency” because you’d end up with poor throughput. Also vice versa. Java’s reputation for poor GC performance is partly due to historical defaults that tune it for throughput.

Go’s GC is already a “concurrent mark-sweep garbage collector” and already has “extremely low mutator pause times, on the order of tens of microseconds”. It sounds like on-the-fly is just a different flavor of what Go already has.