Adapting EF L glass to EOS R. Is it really as good as on a native EF body?

Well I am someone who has really taken a liking to mirrorless cameras for quite a long time now. I have been shooting first Fuji and now Sony along side my 5DIII, and for the last two and half years next to my 5D Mark IV, and prior 1DX. For Sony I am mostly using native FE glass but that is not related to my question just background.

I recently decided to sell my very nice 5D Mark IV because it really wasn't getting used very much at all since I like EVF and the mirroless lighter weight. It sold last week and I hope the new user really enjoys it. I resisted buying an EOS R though up until now because it wasn't as full featured as my Sony's or my 5D Mark IV. Also a while back I sold my most of my Canon primes since I knew what Canon planned for the RF mount and there wasn't an RF mount body I wanted.

So today I still have my key EF L based zoom trinity (16-35/4L, 24-70/2.8L II, and 70-200/2.8L II) plus two TS-E lenses and a 300/2.8L IS v1. I really like all these lenses and only the TS-E adapt well to the Sony because they are MF. The others not so much.

I've decided since the price drop of the EOS R and now availability of even lower priced used ones to buy a body and adapter (with control ring) to use the lenses I have and give it a try. That is if the adapter is really what the claim and seamless. Also like some of the new RF glass that has come out..

So my question, finally, do the EF lenses really work seamlessly on the EF to RF adapter with an EOS R? Or is there hesitation and stuttering when trying to get fast critical focus. Please share your experience on EF lenses you have adapted.
Thank you for your time.