It depends how you define "pause" but no, modern GCs like ZGC and Shenandoah are universally agreed to be pauseless. The work done at the start/end of a GC is f

It depends how you define "pause" but no, modern GCs like ZGC and Shenandoah are universally agreed to be pauseless. The work done at the start/end of a GC is fixed time regardless of heap size and takes less than a millisecond. At that speed other latencies on your system are going to dominate GC unless you're on a hard RTOS like QNX.