I graduated from high school in 2017 and finished the IB program as well. I personally found the IB program stressful because of all the extra requirements you need to do on top of studying as any other AP student. For example, the CAS program as well as the Extended Essay are both things that an AP student wouldn't need to worry about. Those deadlines truly weigh heavy on the mind especially when you're putting in just as much if not more work studying for your end-of-year IB tests. With that said, each experience is what the student makes of it and since everybody has a different experience of IB - some find IB easier and or others, harder. Hopefully that helps. Good luck!
I did the IB program myself in high school and personally found it difficult. IB courses are demanding, and the the amount of material a student needs to know for IB exams can easily be overwhelming for any student. Every student is different, and all students learn differently. Some students learn faster, while others learn slower. Sometimes, a teachers teaching style isn't suitable for a student's learning style. There are many reasons why, but these factors could attribute to why IB classes are stressful and hard for some students. Best of luck with classes, and hope that helps!