React is the front end framework I've used the most when doing front end. It is and was sold as a simple and performant library to build interactive web apps, but things like its virtual dom was a very memory-hungry abstraction that immediately needed fixing.

Over the years we've had a cascade of APIs to convince us that React was easy: shouldComponentUpdate, hooks / useEffect's manual dependency array. It always felt like React spent most of its time solving problems it didn't need to solve in the first place if he didn't create itself those problems by having a not so great hard to use API. State derivation and computed properties and dependency graphs were already solved problems before React came and tried to explain to everyone that it knew better. The irony is that the ecosystem is now going back on signals / observer approach.

Now that I've finished complaining, I will probably keep using it in the future! (or Preact! which i feel always done a better job of reimplementing React or more, the fresh framework from the same author while I think still WIP is really promising too).