Game Freezing Up Frequently

My game has recently become nearly unplayable due to frequent freeze ups. I don't have any mods or cc installed, but the issue started around the same time as the new time travel event, so I don't know if maybe it's related to that. Sometimes it freezes up upon arrival when I travel to a new venue, and sometimes it happens when I simply rotate the screen or move around the lot. It is affecting my ability to complete the event but also just to play the game in general. Also, if I complete an event task without finishing the week, even when I save the game as I go, it doesn't show my completion of the task upon launching the game again after it froze, and I have to do the tasks again. I was hoping some of the recent game updates would rectify the situation but, so far, I am still dealing with the issue. Any ideas?