Increase HeapSize to improve performance

[dr0i]

@TobiasNx discovered in a workshop we held that some people had performance issues.

At bibliocon2023 we used an increased memory allocation of -Xmx6G and didn't experience these performance issues - so this is a shot from the hip but it may well be that it works.
Hm. Does it hurt to increase to 6GB - it doesn't our servers, but what is with others'?
Also, one would want to make a little load test to ack if this is really helpful.