For the technicians among us; my comparison between the 2 “modes”.
In my opinion there is no “evidence” in here for better fps (or ms…), on the contrary 
But the smoothness is still indisputable.
Especially in areas where the fps without the vfr map “open” drops to 20/25 fps (and the stuttering begins)
And it is not a “glitch” effect; the smoothness stays for the rest of flight (or untill closing the window).
I tried the suggestion with other windows (mfd, pfd) and at least for the figures this gives the same effect indeed: did not tried the effect on smoothness with these windows open “in flight”