React done poorly can be slow. Bad code can just force the virtual DOM to diff unnecessarily 1000s of times and your app will still work fine for the most part. That said, if you are intelligent about when you force React to reconcile state changes with the DOM it is very efficient.
All of these frameworks purpose is to synchronize the state of your app with the state of the DOM. There is no getting around that, that is why they exist. Vue uses a virtual DOM with diffing as well, I am not sure how Svelte/Qwik do it but I imagine they have a similar mechanism? Like you can't get around the fact that at the end of the day all of these frameworks exist to say: "The data in the users app updated, what DOM updates do we need to make to reflect that?".
Anyway that was a tangent but, I think React is perceived as "slow" or buggy because the vDOM & reconciler are so flexible that it allows people to do extremely dumb things while coding and it will still work.