The way RAM is managed in Java and in C is very different; neither is better than the other, but it's different, and you don't seem to understand the Java model. In that model, you give an application a maximum heap, which the program will use regardless of the minimum it needs to improve its performance. You want it to use less RAM? Just tell it to. Having said that, very recently Java has started to return RAM to the OS if it's just sitting idle. See https://malloc.se/blog/zgc-softmaxheapsize