Vegas Pro preview lag can be infuriating, especially when the clip plays perfectly in VLC but turns into a stuttery mess on the Vegas timeline. In this video I show exactly what I ran into on Vegas Pro 17: two 1080p 60fps clips from the same phone, yet one pegs my CPU at 100% and chops like crazy whenever there’s lots of movement on screen. The key difference wasn’t my PC or Vegas settings—it was how the phone encoded the video. I break down the fix in two ways. First, if you haven’t recorded yet (or you can re-shoot), change your phone’s camera settings so it records in H.264/AVC instead of HEVC—on my Samsung that’s under Advanced video options. Second, if you’ve already recorded (or even already edited), I show how to convert the problem file using Avidemux: set Video Output to AVC x264, Audio to Copy, and output to MP4 (since MKV doesn’t work natively in Vegas). I also cover the “don’t lose your edits” trick—convert the clip, then rename it to the original filename so Vegas relinks and your cuts stay intact.