GPU is not loaded, interpolation is slow (RTX 3060)

[Egor179]

When interpolating up to 60 FPS (2.4 coefficient), for some reason the video card does not load at all, at the beginning it goes fast, then the speed drops, coolers practically do not buzz, usage is from 0-1%, half a gigabyte of memory is allocated.
With every second the speed is lower and lower
Video source:

Video
Format : MPEG Video
Duration : 18 min 23 s
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 FPS
https://www.youtube.com/watch?v=yLq1RXsIEe4

bandicam.2022-12-20.22-12-02-308.mp4