I’m curious as to why, uou are using that much. I have 16Gb, but just checked and am using les than 1GB and zero swap.
Besides any system stuff, Firefox is running so, I’m not using much, but it sounds to me like a lot of your memory is being used.
Maybe, you have a lot running? What?
I always hear, for the swap file size of, about double phyiscal memory.
Hope this helps.