CRT has zero input lag from signal to phosphor (maybe a few nanoseconds due to speed of electronics and the electron beam itself) but it will take a few milliseconds to scan an entire frame.
With vsync enabled I guess you could have effectively lower input lag from a well engineered 500hz digital display, when considering lag for complete frames.
If the system is fully engineered to race the beam then you can't beat zero input lag for CRT on mid scanline.
