Install the latest drivers from the manufacturer websites. In case of Radeon or GeForce go straight to AMD or nVidia respectively. Not the assembler (MSI, Gigabyte, &c). The GPU driver is the most critical to update.
Other than that. Use an anti-virus which has a low performance impact. Such as Avira. Disable any startup items that are not necessary. Many programs install junk services that don't need to run at startup or for the program to function. Pause cloud sync services like Google Drive. Pause backups. Close any open programs.
Use a program like MSI afterburner and enable OSD. That way you can look at CPU/GPU/RAM usage while gaming. Along with temps. To help you tweak game settings to an optimal balance for max FPS with minimal detail loss. Monitoring temps and clock rate will let you determine if you need more aggressive fan settings or better cooling. As you'll see if you are throttling or at least not hitting full turbo boost.