I like to use overlay option in retroarch to display nice borders when i play 4:3 games on my 16:9 TV.
I was playing street fighter third strike in fba libretro core, it runs full speed at 60 FPS on my Rpi2, even with a simple scanline shader, but when I activate overlay it drops at 48 FPS!
My overlay is just basically an image, how can it have an impact on emulation performances?
because it is liking engaging the gfx processing to simply display that image. it isn’t just loading up an image like your web browser does. its creating a video service most likely and using that to display that image. the size of the image and resolution of the output is like a contributing factor here