Fixing the video playback speed

We had an issue where the video playback was very slow as the quality was too high (4K) to run on these computers, and so I attempted to reduce the quality of the clips.

I imported them into final cut

And then exported a clip in 1080p (Lower quality) for an example to see if it would work

It was successful, although using this method for the rest would be too slow as I could only select one clip at a time and it would have taken a few hours for the exports.

I tried to attempt some alternative methods

 I used a program, Batch Video Resizer, although this came out with a lot of errors, including the video not being playable after the resize was complete.

Next I tried uploading from Windows Movie Maker, it supposedly should be able to export with multiple files, but when I added more than one it began to crash upon upload, I'm assuming it was due to the file size.

My final attempt was on Adobe Premiere CC, Ihad success with this, although the export took around 6 hours for the 14 minutes of footage. It also came out in one clip, so this will need to be cut at some point.