Additional clarification / observation:
To clarify the ~64 Hz component: during each 15–20 second abnormal window, the long/short frame-time deviation itself repeats with a period of approximately 15.7 ms (~63–64 cycles per second), while the average framerate remains around 270 FPS. This does not mean the game is running at 64 FPS; it is a periodic modulation of frame delivery.
I have also seen reports from other PC configurations showing a similarly timed recurring event, but with a substantial FPS drop rather than only frame-time instability. This suggests that the visible severity may depend on available frame-time headroom. Systems running close to their FPS ceiling may show a large FPS drop, while systems with substantial headroom may maintain the FPS cap but still exhibit severe frame-time variance.
Therefore, the absence of an obvious FPS drop does not necessarily mean the issue is absent. On higher-headroom systems, it may primarily appear as abnormal frame pacing instead.
Update – Frame limiter comparison
I also tested the issue using the in-game limiter, NVIDIA Control Panel limiter, and RTSS, all capped at 270 FPS.
The same ~16-second disturbance still occurs at the same highly regular ~5-minute intervals with all three limiters, and the ~63–64 Hz frame-time modulation remains. This further suggests that the limiter itself is not the cause.
During the affected interval:
NVIDIA limiter: Adaptive STDEV ~1.1 ms, 1% Low ~173 FPS, PCL ~3.8 ms
RTSS: Adaptive STDEV ~0.3 ms, 1% Low ~226 FPS, PCL ~6.7 ms
RTSS greatly reduced the frame-time oscillation and preserved much higher 1% lows, making the visible judder significantly less severe. However, this comes at the cost of higher PC Latency.
One result that surprised me was that the NVIDIA limiter actually produced lower PCL than the in-game limiter in my testing. I had expected the in-game limiter to have the lowest latency.
So, while RTSS does not eliminate the underlying periodic event, it may be a useful temporary workaround for affected players who prefer smoother frame pacing and higher lows and are willing to accept a few milliseconds of additional latency.
I’ve attached screenshots of the affected interval with both the NVIDIA limiter and RTSS for comparison.
Isolated graph of an abnormal sequence / RTSS limitter
Isolated graph of an abnormal sequence / Nvidia limitter
