Every time I export (Save Movie), no matter the project or the files in it, every minute or so in the final export, there is a noticeable FPS drop that happens for a few seconds and makes the video choppy and laggy. The first FPS drop will always happen at 1m09s and I don't know how to fix it. The original files are completely smooth, and the playback while editing is smooth also. 

I am using Windows 10, version 2012 build 16.4.3528.0331, files I'm using all vary in frames p/s, dimensions and bitrate which I suspect could be the problem, I'm importing MOV & MP4 files and exporting into MP4. I'm primarily exporting projects using the "For high-definition display" setting (1080p, 29.97fps & 24,000kbps) but have exported using other settings and the problem still persists. 

Let me know any details I'm missing out and I can provide, please help me fix this as this is becoming extremely frustrating. Thank you.