jvm in aix

Sirs

I encounter the problems in this way;

I have the AIX machine installed 1 JVM originally, After I use the dual JVM
(mean 2 JVM per LPAR), the second JVM is always slow and hit the memery
margin.

But if i install 1 JVM per LPAR for each machine, (2 JVM for separate
machine each), there is no problem.

I check and it should not be the CPU usage problem as I increase the CPU to
2 when running dual JVM.

Please help