After Save and Quit, game crashes when re-entering world.

World is 880MB, but crash has been occurring since world was around 300-400MB. I keep two backups. "Copy of Feldswam" (Feldswam is old English for "mushroom" Base is on a mushroom island. (-: ) and "Old copy of Feldwam". To duplicate, I will save and quit, delete "Old copy of Feldswam", rename "Copy of Feldswam" to "Old copy of Feldswam", and make a copy of "Feldswam", creating a new "Copy of". It will hang a long time after renaming the world for a while, then after making the copy, I will re-enter the world. The splash screens will freeze, then either close MCPE and return me to XBox home, or it will shut down my Xbox entirely. I then need to disconnect the power cord for 30 seconds to get it to turn back on. This process I listed took 75 minutes before I could get back into my world. Sorry so lengthy, but wanted to detail as much as possible, because I'm genuinely concerned that this game may someday ruin my console.