There are times when Sims 4 starts using even 60 percent of CPU prowess due to the expansion packs and Mods. However, if the concerned Mod isnu2019t from a credible source, the game might crash or start lagging even if the hardware isnu2019t an issue. Another reason could be the out-dated graphics drivers or the lack of G-Sync that prevents screen tearing at a higher FPS.