the vague part is details about your proccessing that could help suggest alternative aproaches.

I do not represent the group wisdom in these parts, I'm representing nobody but me.

I'm in the lucky position that I've seldom run out of memory, but I have had to consider ways to reduce memory footprint. Once your machine start swapping, you have hit a very real speed bump. How bad the degradation is, depends on factors like your operating systems swap strategy, swap disk speed etc. Also it matters a lot if your process keeps refering back to already swapped out data or not.

Another set of RAM chips might be an inexpensive solution compared to the time needed to develop a better software solution.