(Wikipedia) Totalitarianism is a form of government and a political system that prohibits all opposition parties, outlaws individual and group opposition to the state and its claims, and exercises an extremely high if not complete degree of control and regulation over public and private life. It is regarded as the most extreme and complete form of authoritarianism.
It’s not true that decisions can’t be made quickly by democratic governments. There are truly thousands of counter examples, but to take a single one, in the COVID-19 pandemic, many democratic governments took rapid decisions. Some of these decisions turned out badly and some well, which provides a second stumbling block to your thesis: decisions taken quickly can be bad as well as good.
Secondly, it’s not true that totalitarian regimes act quickly. There’s a governmental bottleneck of the ruler and his clique. If they’re not paying attention to a given issue at a given time, decisions can’t be taken at all, making for less efficient governance. And, in practice, such decisions as are taken are often not implemented: you end up with rune-reading and kremlinology by officials trying to work out what an order ‘really’ meant, or whether it really was an order, because there’s no clear method for governing other than ‘Do what the leader said’.
I appreciate, by the way, that you’re making a devil’s advocate argument, here. Just wanted to explain why it’s wrong, as OP seems pretty disposed to believe the devil!