Here are some links!
mkvtoolnix (whoever invented this name ... ლ(ಠ益ಠლ)) can be downloaded here:
https://www.fosshub.com/MKVToolNix.html
I use the portable version. It allows to split videos without re-encoding BUT it puts the video in a mkv container afterwards. (No problem as Reaper can load them too.)
If you use VLC you can try my extension (still not official because I hate that I would have to create another account at videolan)
More info and download here:
https://forum.cockos.com/showthread.php?t=216099
Greetings
Eli