Multiple issues, Minecraft barely functional

I have multiple issues. It may be connected to my Nintendo. Minecraft crashes constantly for no reason, some templates I load will crash after completing world generation, friends lag a ton when they join me, but don’t when either on a server or if I’m in a world with them, even to the point of crashing, and because I crash so much, playing regularly is nearly impossible. I have lost a bunch of progress on some worlds, especially with add-ons because of this. I have spent money on templates and most always crash, so I am unable to play them. I don’t have any screenshots to help.