Upgrade to Ubuntu 20.04 LTS from 18.04 LTS made system too slow

What can I say? You placed yourself in what the old saying goes “between a rock and a hard place.”
Meaning, I don’t know if I can give any good suggestion. First of all, Please learn from this.
ALWAYS – Take a backup before making major changes to your system. If you don’t know how, learn how to do it.

  1. If you re-install 18.04, yes you will have to install any and all software you want back again.
  2. Read thru this posting. @Irenburg was having slow response time. Maybe it will help.
    Ubuntu 20.10 Slow app Loading
  3. Backup your user data in home or elsewhere before you loose it.