Why does the sound and image lag intermittently in the game?

Question

Video cards

I've been playing War Thunder for a long time, but for several months now, sound and image have been intermittently lagging in battle (FPS is very lame), at the same time. The sound seems to be doubled or tripled and stretched. At the same time, if you turn the game camera to a top view, then the problem may go away until you return the camera to normal view.
The problem usually appears every day, sometimes only 1 time in a few battles, and sometimes up to 6 times a day. At the same time, lags can be either half a minute or the whole battle.

Windows 10
Intel Core 2 Duo E8500 3.16GHz
RAM 8 GB (DDR2)
NVIDIA GeForce 285 GTX (1 GB)