First tell us if you have already allotted the 13 GB allowable to Adobe programs?
Do you run your programs with either an OS performance and hardware monitor on so you can see CPU, GPU and memory and disk loads to tell where things are happening and how much ? Did you download your computer manufacturers hardware monitor to keep tabs on loads while you are working. Knowledge is a powerful tool. More RAM will not help if you do not have Adobe prefs configured.
So make sure you are using all the RAM you can in your program use.
Also if you buy more RAM look at RAM speeds. Chip spped and bus speed is limited to the slowest chip on the Bus. So do not Max out just the size, max out the chip speed. Generally CPUs are able to deal with faster bus speeds than the RAM the machine ships with. Keeping you in the dark allows them to keep selling more RAM.