How can I make Java application run with more memory?

I have a computer with 32 GB of RAM.

I am testing a software and I can see that it starts to work slowly when device manager says that it is using more than 6000 and something MB.

In the log file, I can see:

name of the application, running on 8 cpu cores and 6367MB memory.

I have followed this tutorial and setted 24576MB but it still doing the same.

I just have the binaries, not the code.

Any solution? Thank you.