The new OS did not install correctly on top of the old one?

Question

linux

Good afternoon. Essence of the question - I tried to reinstall the OS on the user's PC from Linux Mint to Astra Linux. The problems began at the beginning of the installation - it lasted a very long time. After reinstallation, the system is extremely slow, the mouse moves jerkily, windows open 20 seconds after startup. I sin on iron. An SSD is installed on the PC, and a mat. board from Asus, before installation there were dances in the BIOS settings, disabled secure boot, UEFI is a priority. The installation was carried out from the distribution kit on the disk. What is the installation problem, where to look?

Answer 1

If the system is installed, can there be problems with the installation? She's done.
But in order to understand why it works slowly - there is not enough data at all.