use optifine its a mod it change my fps from 10 to 50!

 

I also suggest optifine. Look it up on google.

 

Optifine probably wont sourt out everything. The problem is your pc. If getting a new one os out of the question ( waste of money in my opinion) try rebooting your computer ( is that the english word? Hope so) u can make a safety copy of ur important files into an external hard drive. Also, when reinstaling apps in ur pc only install the essential ones like browser (google chrome), apart from the operative system and do not set them to open when the computer starts. Also, chek if some programs are using too much RAM cuz if so, delete ir or replace it with a lighter program.( note that some antivirus are very heavy like panda). Dont run MC with other programs opened and dont stuff ur computer with too many files-get a hard drive. If i said anything wrong plz correct me

 

When your partner played minecraft, was it with a different computer/laptop?

It if was, that suggests to me something is up with your computer/laptop. My advise in this case is many suggestions:

• Close background programs, they use PC resources and possibly Internet connection.
• Update any anti-virus, firewall or adware/spyware applications and run a test with that.
• If you have the programs above, and they didn't find any big problems, I tend to uninstall, remove any saved data and reinstall - you'd be surprised at what it finds if its a good program.
• If you dont have the three programs above, get them and preform full scans - be prepared to waste the day away with this.
• If this happens hopefully you will find some bad things that is the cause of all these problems. If it isn't, the last suggestion would be to clear the java cache.

Hope this works!