Of course it’s a placebo effect! 
. FSR2 merely reduces the resolution the sim needs to feed the GPU and then upscales it to your monitors native resolution. So in the screenshot below with FSR2, it only requires 2560x1440 from the sim and then the GPU upscales it to 4k (btw I also have HDR10 turned on and vsync in the sim capped at 100fps). The CPU works less as there are not as many pixels it needs to feed the GPU. I believe that FSR2 is the equivalent to Nvidia’s DLSS 2.
