Tweaks to give ipfire more ram

I am running ipfire on a 1U core i7 box with 8G of ram. Literally 7 GB of ram are free. Are there any memory settings I can adjust in for the kernel to use more cache ? I have all this extra ram and would love to give it to ipfire to use for whatever it wants.

Please read this. Especially the “Size Matters” section:

You simply have too much RAM. This is a firewall. It moves data, it does not store it. It will use the memory when it needs it.