Comsol does not use all RAM available

Dear all,

running Comsol on my laptop, I see that it uses only 4-5 Gb of the available 16Gb RAM, and in fact it takes a very long time for simulation of time-dependent 3D problems. I don't have any other process running in the meanwhile.
I made sure to use the 64-bit version as well, but nothing change, again the available RAM is not fully exploited...

Thank you for any suggestion

Regards
--
Fabio