I was in the middle of a build and the game starting running super slow. I had about 30 tabs open on my internet browser. I closed those out and also closed the game out and restarted it. It was still super slow. I restarted the computer, same problem. I ran malware and virus scans and got it clean.
It finally started running normal speed. I was continuing my build, then I realized that it didn't save some of my progress and had to redo the build. I rebuilt it, saved the game and reentered the game. Again, it didn't save my progress. I tried this several times and I kept opening the world up in the same spot with the same progress not saved.
Also, it only renders about a 100X100 area. Each time I close and reopen the game, it adds a few blocks that it will render.
I tried opening another world and it everything worked perfect. It rendered, and saved my progress.
What in the world is my problem?
Give me instructions as you would a kid. I'm not extremely computer-literate.
Added (1). Since it was happening only to the 1 world, and not to any others I tried to troubleshoot.
I put the world on a flash drive and opened it on another computer with Minecraft installed. The problem persisted. Therefore I know that the problem is with the world and not with the game itself.