I read here about the fees difference when paying to many addresses at once instead of doing it one after another. I was wondering whether this applies to the transaction time as well. Is it significantly faster if paying to N addresses at one? If so, could you please give an example, say N = 20.
For all transactions, "transaction time" is effectively 0. A transaction is created nearly instantaneously and broadcast to the network with no noticeable delay to a human.
What you are confirmed about are confirmation times. The time it takes to get a confirmation is only related to the transaction fee rate paid and the time it takes to mine a block. The size of the transaction is irrelevant.