Others took a little longer because the three judges needed to deliberate, and some needed to go through an entire line of questioning before they were found innocent enough to live.
On average, each vampire took somewhere between one and two minutes to judge, causing the entire procession to quickly dissolve into an assembly line of judgement, where speed was preferred over deliberation.
The only ones really slowing things down at all were Liv and Astrid. They still considered these vampires to be their people, after all. But there was simply no denying that they were all vampires, rather than ghouls, which meant they were complicit in Sigurd's rule in one way or another.