Slow Loading Time For 3 Out of 9 Sheets

I have built a preview process for Marketing Materials that contains 9 sheets. The sheets contain automations and not all sheets are connected.

All of the sudden 3 of the 9 sheets are taking 5 minutes or more to load. It is happening for the entire team, not just myself. It happens a home and in the office. It started with just 1 sheet, then a month later another started doing it. 6 months later the 3rd one started. The team is starting to complain.

What causes this? How can it be fixed?