Reading and writing is not slow, but your queries. If you don't cache or optimise your queries then any operation is going to be slow. With a VDOM you are just

Reading and writing is not slow, but your queries. If you don't cache or optimise your queries then any operation is going to be slow. With a VDOM you are just exchanging queries for cached DOM objects, but if you don't optimise your updates on such they are bound to be slow as any other. Also, a VDOM is immutable and prone to garbage.