I tried to keep it simple here, but doing a rough measurement of `time make check_java` x 3 gives the idea:

```
before:

real  0m24.713s
user  0m39.545s
sys 0m1.962s

real  0m24.992s
user  0m39.570s
sys 0m2.082s

real  0m24.166s
user  0m38.705s
sys 0m1.842s

after:

real  0m20.365s
user  0m31.869s
sys 0m1.781s

real  0m20.593s
user  0m32.733s
sys 0m1.858s

real  0m20.576s
user  0m32.992s
sys 0m1.763s
```

This mini-benchmark of the tests isn't indicative of typical performance, it is bottlenecked by JVM startup cost for each language.

…tions when running tests