Garry's Mod is an open-ended physics sandbox built on the Source engine where players spawn and manipulate props, NPCs, vehicles, and tools from Half-Life, Counter-Strike, and other Valve games. Most players spend their time on multiplayer servers running community modes like DarkRP roleplay, Trouble in Terrorist Town, Prop Hunt, or Sandbox free building. These sessions are driven by whatever the players create in the moment: towering contraptions, scripted weapons, custom models, and hundreds of Workshop addons that must stream in on the fly. At 1080p, the GPU load stays modest even with textured mods, so performance problems almost always trace back to the CPU and system memory rather than raw graphics power. High prop and NPC counts, overlapping physics calculations, and heavy Lua scripting quickly expose the engine's single-threaded legacy behavior. Stuttering during massive builds, lag spikes when someone starts a "prop war," and long loading screens from addon-heavy maps are the most common complaints. Players also frequently underestimate how much RAM and fast storage Workshop content actually uses, leading to hitches that make precise building or responsive roleplay feel frustrating. Before choosing a PC, understand that Garry's Mod performance scales with player creativity far more than with fixed game content. A system that feels smooth on a lightly modded server can bog down once a popular multiplayer lobby fills with custom assets. The 64-bit branch has improved multicore use, but single-thread clock speed and memory bandwidth still matter most for avoiding those annoying physics hitches and keeping server sync responsive.