I've had this problem for ages ever since I started VR in DCS. ST or MT.
Quest2 and now I'm on the Quest 3 and same problem.
2 separate computers in different parts of the country.
Intel 13700K, 128Gb Ram CL30 6000Mhz, M.2 dedicated drive. 4070Ti
and the other,
Intel 14700K, 98Gb CL32 6400Mhz, Dedicated M.2 , 4080.
Have set 72fps as max on everything which is lovely to pay on but as soon as I go to the F10 map, it goes down to as low as 6fps sometimes but most of the time sits at 12fps. After a while it might clear and go back to normal 72fps.
I'm chasing my tail here.