I have, since the very beginning (more than 3 years ago) it's at 34000MB, I think it's plenty, isn't it?
experienced it with windows 7, 1080ti goes down to 18MH after i added another 2gb (system is 6gb), it is back to normal..try adding system ram.
increasing virtual memory did not work for me...
today rigs with 6gb and 8gb system ram returned to 18MH, but it is now a miner software issue, the fix is gminer 2.38