[0.16.51] The problem of playing on a discrete graphics card

[mozk666]

This game I is not played for half a year , decided to download and play again, before the problems did not arise.
The laptop is relatively old, but coped with the games and now copes with most MMO and AAA projects.
The problem arises only when playing on a discrete card, from the very beginning of the game it is impossible to play normally, the game shows 5-10 fps, all friezit, the CPU at the same time loads 5-6%, and the video card is 80-90%, enough RAM, takes the put 4 of 8 GB.
But if I'm playing on an integrated graphics card intel , then such problems do not arise, but problems arise after heavy load , but it's an understandable problem , CPU already not pulling.
what could be the reason ?