Dollar for dollar, a RAM clock or capacity upgrade has the lowest impact on game performance, unless of course you are upgrading from DDR2 500 MHz to DDR4 2666 MHz or something like that. In general it is mostly GPU, CPU, HDD transfer speed and RAM loosely in that order. I doubt any modern games will get a huge FPS boost by upgrading the RAM from 1600 to 2000 MHz.
problem, this sounds very similar to a memory leak.
Trying updating the game and the drivers, usually leaks are fixed by updates.