Bottleneck
A bottleneck is the component that limits overall system performance, leaving faster components waiting because the pipeline can only run at its slowest stage.
Also known as performance bottleneck, limiting factor
Measured by SystemCheck
Part of the four-stage run: a 60-second sustained CPU load reporting throughput, decay and consistency; a memory stage reporting bandwidth and latency; a calibrated GPU raster load reporting frame time, pacing and decay; and a path tracer reporting samples per second. The paragraphs below say which metric carries this term.
Every system has a bottleneck at every moment. That is what it means to be at capacity somewhere. The useful question is not whether one exists but whether it is in the right place for your workload, and whether it moves as conditions change.
Bottlenecks shift with settings. The same PC is typically GPU-bound at 4K with high settings and CPU-bound at 1080p with low settings, because resolution scales GPU work while leaving CPU work roughly constant. This is why "bottleneck calculators" that take two part names and emit a percentage are meaningless. The answer depends on the workload.
The reliable method is measurement: watch which component sits at high utilisation while the other waits. SystemCheck helps by measuring CPU and GPU capability separately under sustained load, so you learn each side's real ceiling on your machine rather than inferring it from spec sheets. Combining those with in-game utilisation monitoring locates the bottleneck for a specific title.
Related terms