I sometimes get temporary freezes that resolve themselves, and I think it's not unusual. One common culprit for me is when my sims are exploring a tomb and they do something to trigger the opening of a staircase—the game almost always locks up for a couple seconds before the animation and music play. This has happened on two different systems, so I think it's either the game itself or something about newer graphics cards, not an issue with a given install or save.
There are different reasons for a lockup like that, but it's probably related to the game engine needing to calculate something and basically dropping all other functions until it's done. Whether the effect is temporary or permanent may depend on whether the game engine can resolve the issue or not, or these may be two separate problems. Speeding up the game clock can definitely contribute as well, since faster speeds mean more calculations in a shorter time frame.
So the question is what exactly was happening in-game when the freezes happened, what time of day was it (for example, was it 5 am when plants would grow or bear harvestables, or maybe 8 am when sims would be going to work, etc.), or are there any other patterns that you've noticed? Do you currently use mods, and if so, which ones, and do you have any custom content? It's possible there's an obvious, avoidable trigger, but it's also possible that there's no single cause, and you'll just need to take a couple steps to try to prevent the issue.