That's just in one specific sim Atlau, it depends on your detail settings in DCS regarding VR. 45fps is typically what the VR units drop down to under high detail settings in certain conditions on screen, it's pretty rare to maintain 90fps in the Rift or Odyssey/Vive 2 with their higher rez screens, for anything other than very high altitude and not much going on sort of conditions in game.
AH3 I haven't tested VR in a while, but keeping high FPS was much easier, and AH3 IMO still has the best cockpit VR implementation of any game out there.
Outside of VR, where the 2080ti has also helped in the FPS department is with 4k LCDs, I have one 4k 144hz Asus PG47UQ right now, and the 1080ti had problems maintaining over 100fps in quite a few games at times I'd noticed @4k on that monitor. 2080ti has increased performance by about 25% I'd say in the games I've run on it so far. When the 65" nVidia 120hz 4k come out, that'll be where the 2080ti will be worth the $ over the 1080ti...maybe. We'll see.