How to Measure FPS and Frame Times Before Changing Game Settings
A frame counter tells you how many pictures a game delivers each second. A frame-time graph shows how evenly those pictures arrive. Use both when you want to know whether a settings change actually helped.
Start with a familiar scene
Enable the performance display supplied by your game. If it offers a frame-time graph, turn that on too. Pick a saved checkpoint or practice area. Write down the resolution, graphics preset and power source before touching any settings.
Read the graph
At a steady 60 FPS, each frame takes about 16.7 milliseconds. A single 50-millisecond frame takes three times as long and may feel like a hitch even when the average looks good. Note where spikes happen. A repeatable spike at a doorway tells you more than a momentary peak on a loading screen.
Compare two runs
Follow the same route twice to establish a baseline. Change one option and repeat the route at the same pace. Record the typical FPS, the rough number of visible hitches and whether the image still looks acceptable. If the difference between settings is smaller than the variation between repeated runs, call the result inconclusive.