Performance load is a concept that explains what happens when you have too many things to do. Above a certain point, the more tasks a person has to do, the more their performance on all of those tasks decreases.
If you want to be productive, you must set limits. Juggling hundreds of active tasks across scores of projects is not sustainable: you’re risking failure, subpar work, and burnout. Remember Parkinson’s Law: if you don’t set a limit on your available time, your work will expand to fill it all.
The default mind-set of many modern businesses is that “downtime” is inefficient and wasteful — workers should be busy all the time. Unfortunately, this philosophy ignores the necessity of handling unexpected events, which always occur. Everyone only has so many hours in a day, and if your agenda is constantly booked solid, it’ll always be difficult to keep up with new and unexpected demands on your time and energy.