We have developed a simple video player Swift application for macOS, which uses the AVFoundation Framework. A special feature of this app is the ability to play the video backward with speeds like -0.25x, -0.5x, and -1.0x. MP4 video file is played directly from the local file system, video codec is h.264, and audio AAC. Video files are huge, like 10 GB, and a length of 3 hours. Playing video in reverse direction works well on a Macbook Air with M1 or M2 chip. When we run the same app with the same video on a Macbook Air with M3 chip the reverse playback is much worse. Playback might stutter badly, especially in the latter part of the video. This same behavior also happens in Apple's Quicktime video player when playing in the reverse direction with -1x speed. What's even more strange is that at one point of a time, the video playback is totally smooth, but again, after a while, the playback is stuttering. For example, this morning reverse playback worked 100 % smoothly, then I rebooted the Mac and tried again: the result was stuttering. After this the Mac stayed idle for several hours and I tried to reverse play video again: smooth performance! My conclusion: M3 playback works fine if the stars in the sky are aligned correctly. :-) So it's not only our app, but also Quicktime player is having exactly the same behavior. And only with the M3 chip. The same symptom appears with another similar M3 Mac, so it can't be a single fault. At the same time, open-source video player iina can reverse play the video well on the same Mac. All Macs have otherwise identical configuration: 16 GB RAM and macOS 15.1.1. Have you experienced the same problem? Any chance to solve this problem? I really hope that the M4 chip Mac is behaving better here.