Some actions freeze time, like opening your inventory, pickpocketing someone, opening your favourites etc.
Recently I was going to talk to someone, and I noticed someone else I hadn't spoken to, so I spoke to them first. By the time I'd finished, my first target had wondered off. I thought that speaking to someone would also freeze time, but it didn't, causing me to lose track of someone.
What actions in this game cause time to freeze?