I’ve been having this issue since the Jan 25th update. Anytime I load into a save, within a couple of seconds my sims freeze and will not do anything, qued up or not. The clock continues to move but ...
Ideas
The problem with this type of issues is that there's about a million reasons why it can happen and it's very difficult to troubleshoot or pinpoint a specific reason.
You have an older mac and it's probably best if you post in the mac forum: The Sims 4 Technical Issues - Mac | EA Forums
You get far better help there from folks that understand Macs.