Module with 25k source files - can't compile with eclipse compiler - 5g heap already assigned

Hi,

I try to switch from eclipse neon to ij ce 2016.2.5. The eclipse project has around +25k source files. After importing the project I wanted to run a unit test and encountered some memory issues while the module was compiling. I already switched to eclipse compiler and assigned 5g memory and -XX:+UseG1GC with no success. Eclipse runs and compiles with 3g. Can someone help me getting things work with IntelliJ please?

Regards

Dennis