The five-minute diagnosis that explains why lowering settings sometimes gains you nothing.
Every frame is a relay race: your CPU prepares the frame (game logic, physics, draw calls, other players), then hands off to your GPU to draw it. Your FPS is set by whichever runner is slower. This is the single most useful thing to understand about PC performance, because the two bottlenecks have opposite fixes.
Open a monitoring overlay (MSI Afterburner, or the built-in overlays in Steam, AMD Adrenalin or NVIDIA's app) and look at GPU usage while you play:
An even simpler tell: drop your resolution one step. If FPS barely moves, the CPU is the wall.
CPU-bound situations:esports titles at high frame rates (CS2, Valorant, Dota 2 — pushing 300+ FPS is almost purely a CPU exercise), open-world city centres (Starfield's towns, Baldur's Gate 3's Act 3, GTA V traffic), large multiplayer battles (Battlefield, PUBG), and simulation-heavy games (BeamNG.drive's physics, Microsoft Flight Simulator). In our crowdsourced FPS reports these are exactly the games where real-world frame rates diverge most from pure GPU expectations — which is why FrameCoach models a per-game CPU ceiling on top of the GPU estimate.
GPU-bound situations:almost every demanding single-player game at 1440p or 4K, anything with ray tracing enabled, and any game where you've stacked resolution and quality settings beyond your card's class.
The settings that feed the CPU are the ones that control how much stuffis in the scene: crowd density, population/traffic sliders, draw distance and object detail, physics quality, and in some games shadows (shadow-casting objects each cost draw calls). Frame generation (DLSS 3 / FSR 3) also helps specifically here, because the generated frames don't need CPU work. Beyond that, the honest answer is a faster CPU — which is why the optimizer tells you when a game is CPU-capped on your processor instead of pretending settings will fix it.