Something's wrong with my Minecraft?

On singleplayer, all of a sudden I can't load or create worlds, I just have to quit but in the Output it says that I joined the world when I just froze actually.

On multiplayer, when teleporting from one area to another it takes like 20 seconds, and in that 20 seconds my Minecraft says "Not Responding" at least twice, before I finally teleport.

Can someone help or suggest what might be the problem? This is driving me nuts.

I have a Cybertron gaming computer but it's running behind on games. What do I need?

As I said, I need to find some software for my computer. It's a legit gaming computer, but I can't seem to play games that I should. I was promised to be able to play top notch games (The newest) till at least 2016. I know it's pretty close, but it's been going on for months! Like The Ark: Evolution Evolved, as an example, I have to turn the graphics down to bare minimal and it still lags like hell. That is just one game. Minecraft, The Forest, League of Legends, Starcraft 2, World of Warcraft, and more are not working at the best if their capabilities like promised. Now I asked Best But about it, but they just gave me a list of stuff for me to buy, of course -.- . Now I know I'm gonna need to buy stuff, but if anyonne can tell me EXACTLY what I need to buy or do to my computer to make sure it can play games up to date perfectly and smoothly, that would be lovely. I'm starting up a youtube channel and I wanna try to get an edge. Been planing this for three years, I don't want to have my lack of technological knowledge prevent me from starting up my channel.

How to download minecraft Forge and run it?

I know where to go for the website on downloading, and i know what to do to get it to download, but whenever i try to open the download it just gives me a file. It does ask me what to open it with, but i have no clue what to select, so far anything i select doesn't work… Do you know what program i need to run it on for Minecraft Forge to work?

Would the Acer Aspire XC Compact Desktop be able to play minecraft?

I'm thinking of getting this computer but I want to be sure it'll at least be able to play minecraft on moderate settings.

Added (1). More info here. It features a 1.6GHz Intel quad-core processor, 8GB of RAM and a big 1TB hard drive. Stay connected with USB, HDMI, and Ethernet support.