My garbage lenovo desktop has 4 GB DDR4 2400Mhz memory and an A9-9420 with R5 stoney ridge integrated graphics and a 1TB seagate hard drive. I tried deleting useless pre-installed windows apps, Switching to high performance mode and finding apps that use lots of memory and deleting them. I just want to play left 4 dead 2 at low setting at 1080p, what should i do to free up memory and speed up my computer?