2v2 team mid-game stutters

When I play a game like this:

  • 200 units
  • 2v2
  • AI player in my team, AI players in other team

as time increases, FPS decreases until game stutters so much that it becomes unplayable. I’ve tried lowering resolution, graphics detail and so on with no result. My graphics cards are:

  • GeForce GTX 1050, 4 GB VRAM (used for the game)
  • Integrated Intel HD Graphics, 16 GB shared RAM
  • CPU is Intel(R) Core i7-7700HQ CPU @ 2.80GHz, 32 GB RAM

Previous versions of the game had not this problem, it ran smoothly.