A few days ago I had an update to PowerPoint and it's been running better, but still not what it once was. I've noticed that it will stay open and last about an hour before crashing.
Similar to someone else in this thread I'm in pharmacy school and take notes on my iPad and write hand notes later on as there just isn't time during class. I'm using the Microsoft subscription through the school.
As I stated earlier, I was using PDFs to write on, but that wasn't ideal.
I did download and pay the $30 for OfficeSuite and it works quite well, just the writing is different, and sometimes when opening the ppt later on the writing doesn't line up. You also cannot lasso select in the OfficeSuite app.
I personally find Keynote and Google Slides to be a complete pain.
I've also learned that opening documents off of the files app tends to work better than opening them through PowerPoint or OneDrive and that occasionally going into settings » PowerPoint » Reset PowerPoint has been helping it run faster.
Hopefully, this helps someone as this issue has been extremely frustrating.