@NONOGamer12 I started a thing about a week and a half ago wherein I would do 1,000 solves on 4x4 by doing as many as I could per day. Before this, I averaged roughly 1:20, but now I average 1:03 (as of today). Before starting, I'd done 700 4x4 solves, and now I've done 1,200-ish. I would recommend learning Yau and 323 edge pairing, then doing as many solves as possible to get faster.
If you want a new main, I'd recommend the YJ YuSu v2 M (or the MAX AoSu WR M if you have the money). Performance-wise, they are about the same at first, but I think the best sign of how well a 4x4 is is how well it corner cuts and tensioning, directly followed by how well it handles OLL parity when you're going quickly.
I don't think there are any cubes on the market that can do the last one perfectly, but I'm able to slow down a little bit near the end of the alg to avoid internal pops on the MAX cube. Overall, it just comes down to practice, and if you want to get better at lookahead on 3x3, big cubes and megaminx are the best ways to do that in my opinion.
@Imsoosm it really depends on you. If you think you should get one, definitely get it. I can't personally recommend it since I don't have that cube yet, but I think if J Perm mains it, that's probably a good reason on its own.
The real most frustrating time when your trying to get sub 50 is 50.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000