Yeah, but I think I know why, too. There are many that believe that the crash issues are related to the Vita's RAM. While the Vita is a beautiful and wonderful portable gaming system, even capable of playing console quality titles, it does have it's limitations. One of those limitations is only 512 MB of RAM. Why is that important? I'll tell you. First, when you create a brand new world, it takes a lot longer to create a new world than to load an existing world, especially a large world. That makes sense, since it is creating a brand new world and placing all those blocks. But when you load your world, I believe that the entire world is loading all at once. All of you who have experienced a crash on Vita, answer this:
1.) Is your world large?
2.) Have you just explored (uncovered a significant portion of the map)
3.) Have you just acquired a decent item (in addition to the exploring)
4.) Have you just fought a boss, or a has a major event occurred? (Major event = Goblin Army, Meteor landing, possibly blood moon)
5.) Have you removed a large amount of blocks from the world (similar to the uncovering more map)?
Since the entire world loads at once, the Vita is keeping track of each and every block, enemy, and event. And when you are playing on a large map, that can be quite a lot. By the way, I have not yet experienced a crash on any of my small maps. So, if you uncover a lot of map, remove a lot of blocks, add a lot to your inventory, or a major event, it could overload the RAM. Turning off the music helps in that that's one less thing that is taxing the RAM, but here's what happens after you defeat the Wall of Flesh.
After you defeat the Wall, the entire world changes, even before you break any demon alters with the PWN Hammer. Another corrupt (or crimson) is added, and the Hallow is added, in addition to all the new Hardmode enemy types. There is a new effect that appears to be a bug, that happens after this. Sometimes, if you attempt to save, you will not be able to. You will click on save, but nothing will happen. And if you click exit game, and then click save and exit, you will see the save/load screen, but you will not see a progress bar. But here's what is happening. The data is still being changed. So when you go to click save, it is still undergoing a data process, and it will not let you save. Just wait. The first few times, I had thought that the game was crashing differently and kept resetting and refighting the WoF. But then I decided to try something different. After I clicked save, and nothing happened, I waited. It took over ten minutes, but finally, the save icon appeared in the bottom right. The next time, it only took five minutes. It only did this a few times after defeating the WoF, because the world was still adjusting, each time less and less. And the crashes started happening again. Once again, the RAM was being overloaded. I had even tried turning the wifi off and setting the Vita to airplane mode, but it still crashed. So far, here's what helps. Save often. Do not click exit and save, just click save. When you exit to quit playing, or to visit another world, click exit without saving (after you save, of course), because I've seen it crash more in exit and save than I have with just save. Anytime you are about to change the world (build something, lay out traps, mine a great portion), save before, save during, and save after (basically save a lot more often).