if you exit the game and start the game over and it fixes the problem then the leak is in the game.
(most common for a paged pool memory leak)
if you exit the game and the resources are not returned to the system.
you want to confirm who is using the resources and that they are indeed in paged pool.
Maybe run poolmon.exe and look at the pool tags that have excessive pool used and google the pooltag name to find the list of drivers that use that tag.
most people just jump to the only potential fixes they have. Update the graphics drivers, update the game software and make sure windows update has run and all the updates applied.
if the pooltag shows that the antivirus software is what is using the memory and the scanner is slowing the game, you might disable the software and see if it helps.