Game freezes, CPU 100% busy, appears that two javaw.exe running and competing with each other

Approx. first week of January, game became very slow, non-responsive, "jerky", and nearly unplayable. For the moment, exiting game and reentering would clear that up for a short while, and then same problem. This has been growing worse until now the game just starts off unresponsive, and when you can move, it does not recognize any changes to your inventory, or blocks removed, it just repaints them. It also seems to dump your inventory above the hot bar as well. Tried to do some troubleshooting and noticed that there are two javaw.exe running competing with each other for CPU which drives the CPU to 100% busy indefinitely. In addition, now there are large chucks of land missing that used to be there (approx. 32x32x32). I am relatively new to Minecraft, have not created a issue before, and do not know what to search for in order to tell if this is a duplicate, so please be kind and patient with me.