Using HEVC is causing the big slowdown. Try Slide Deck (H.264) which will be faster and the same visual quality, yet still be a significantly smaller file than a typical H.264 export (usually by a factor of 10).
I’ve not used it with LINUX - but with WIN 10, I do a full re-start of the computer, start ONLY SHOTCUT and do the export. Mine take about 1½-2hrs though (for a 1¼+/- video from 2 or 3 .MTS files. And having restarted, I can save export time by up to 30%.
The other factor - the more FILTERS you have in use have a considerable effect on export time.
I’ve just added RAM to mine 2 days ago (8->12), so it’ll be interesting to see how that helps when I download this week’s 2 Church services in a couple of days.
Alan, I do not use any filters (have not learned about). I have tried a few export options and I think I’ll YouTube w/ hardware encoding since that it is ending up there. Seems to have reasonable time and file sizes.