Premier Pro triggering full-blast fans on my computer, despite extremely basic project content

I am using Adobe Premier Pro 2024.  I have an iMac that is 1 year old.  Processor: 3.3 GHz 6-core Intel Core i5. Graphics: AMD Radeon Pro 5300 4 GB.  Memory 8GB 2667 MHz DDR4.  I just downloaded Premier Pro and I am assembling really, REALLY basic clips to make a movie.  NO sound, NO video. Right now I have 3 layers:  one is a title card, one is text that appears in the title cards, and the third is an adjustment layer with sepia coloring.  20 second into this “movie”, the fans on my iMac ramp up louder than any computer I’ve ever used in my life.  It nearly sounds like a hair dryer.  How on Earth could such a simple collection of graphics tax my computer so significantly?   I am completely baffled, and don’t want to break my computer.   What could be going on?