Did you do any profiling to see what part of code takes most time?
From there we can go on and try to figure out best parameters you could use.
But with so little info it is hard to suggest any changes to configuration.
What is slower? each request takes more time to complete? server with on "same" hardware has lower throughput.
what kind of throughput you are talking about? What is the OS, what is jvm, what kind of parameters do you use for JVM.
in short too many possibility to tell what and how to tune things.
You should start with monitoring the JVM GC and if there is no big issue, log the entry and exit from your methods to see where the time is spend