Ubuntu 20.04 becomes super slow
System "freezes" are often caused by running too many, too large programs and running out of available memory. Use free to see if you have swap space, read man mkswap swapon fstab to create some. Swap space must be contiguous. use mkswap or fallocate, not dd. Traditionally, swap space of 1.5 × RAM has been recommended, but YMMV. If you don't plan to hibernate your system, you can have less than 1.0 × RAM.