preact is usually slower than react actually. Initial load may be slow, but not overall performance.<p>Also preact are very often simply not work, i can't explain, but it is always something really creepy happening in random places. Event listeners also behave somehow different.<p>Also React 17 sets only a single listener to a document, not everywhere and adding a lot of listeners is much cheaper now.<p>At the same time most of the react slowness is not from react, but from awful libraries, usually css-in-js. And concept of css-in-js is actually very good, but implementations are simply awful.