Not only perceive, it is often multiple frames from multiple lag sources (input lag of the USB controller or even worse Bluetooth, display lag from the monitor, rendering lag from the emulator, framebuffer lag).
Playing fast paced games with frame perfect movement (Megaman on the NES for example) is so much harder on a emulator with all the lag, even on very recent hardware.
Not only perceive, it is often multiple frames from multiple lag sources (input lag of the USB controller or even worse Bluetooth, display lag from the monitor, rendering lag from the emulator, framebuffer lag). Playing fast paced games with frame perfect movement (Megaman on the NES for example) is so much harder on a emulator with all the lag, even on very recent hardware.