Tobirama was able to defeat Izuna with his space-time slash attack. Izuna's mangekyou sharingan might have been activated at the time, but even so, he was still subdued. What I want to say is, that scene showed how the sharingan / mangekyou sharingan could not keep up with space-time ninjutsu.
Another scene that proves it was that when Tobi tried to materialize Minato with his sharingan. However, Minato's space-time ninjutsu was fast enough to escape the premature attack.
What do you think guys? Space-time ninjutsu is faster than the sharingan's advanced visual prowess.