Looking at the memory column, it looks to me like Java benchmark uses a large heap to avoid deallocations for most of requests. This means less but larger garbage collections and reduces average time while increasing 99% where the GC shows up.

A long time ago I had to implement a real time service with Java. The best solution was to use whopping 16 megabytes of heap so that it would do a full GC multiple times per second but each of the GCs lasted less than a millisecond.