I think that some members here in the thread already pointed it out. If you have a potato pc running your OS I don't think there is the point of upgrading your PC to Windows 10. If you are upgrading an OS to Windows 10 might as well upgrade your PC, a lot of people are already complaining that they are getting blue screened because the new Windows 10 OS is Ram heavy and I don't think old pcs with 8gb or less ram can handle the requirements of such OS. That's why people here are suggesting to upgrade their OS to a much lighter weight OS such as Ubuntu and Linux.
I tried it on a potato laptop running on 4GB RAM, no issues.