Setting performance budgets doesn’t need to be complex or confusing, you simply need some existing data, some monitoring, and to remember that budgets and targets are two different things. Don’t make life difficult by treating performance budgets as aspirations.
"If you’re building a web experience and want to stay fast, a performance budget can be critical. For success, embrace performance budgets and learn to live within them. Network & CPU limits on mobile can require asking hard questions like, “what is really important to my users?”"