Frame Time Experience Analysis WarHammer
Total War: Warhammer
Above, the percentile chart of the 30 seconds gaming @ 2560x1440. Here we plot FPS and place it in relation to percentiles. 50% of the time measured frames is doing roughly 50 FPS, which would be the average framerate.
On this 30 second run the graphics card manages to remain below roughly 30~35ms (here lower is better), we see no stuttering visually. However you can see much more frame pacing differences, I am not quite sure what that is. Once we get a DVI capable RX 480 we'll re-visit this with FCAT and zoom in and analyze the results, but the behaviour you are seeing definitely is to be considered odd.
With this chart, lower = better as the faster one frame is rendered, the lower latency will be. Huge spikes above 40 ms to 50 ms can be considered a problem like a stutter or indicate a low framerate.