Win 10 Photos, like most other editors, will re-encode and reduce bitrate of your file.
The only real deal is Avidemux. It navigates by key frames and simply splices the video, no re-encoding done, simply copies a part of the file. I'm using it to cut storage space for tandem and aff videos.
True, the interface is a bit awkward, but if you get the hang of it it's almost as fast as just copying the file. That fast. Here are a few tips:
- for mp4 videos (gopro) select MP4 Muxer under Output Format on the left side, and then go to Edit in the menu bar and press "Save current setting by default", to make that setting stick.
- use Ctrl+O to open a directory. It remembers the path. For instance, use it to open a file on your card reader, and next time you plug in your card, just press Ctrl+O to open the card directory and open the video straight in Avidemux without copying it locally.
- use Ctrl+left/right to navigate key frames. These are the places where you can cut your video from.
- press Ctrl+PgUp/PgDn to set the begin/end markers.
- press Ctrl+S to save the trimmed file on your PC. It will spend no time re-encoding, all the time needed is to write to disk the trimmed file. It again remembers the path.
This way you can use Avidemux to get a trimmed version of your video quicker than most users will take to just copy the original file to their computer.