In theory he might be
But Oda so far have only shown sanji blitzkrieg vs non speedsters
Yeah, but we saw how queen reacts to Marco, and from his brief fight with him we can rank sanji's speed in comparison to Marco's
And that's Marco's attacking speed
And sanji is clearly above Marco in that regard, I don't know if many people realize this but sanji's new power ups are just insane
For a few seconds he straight up has speed on par with kizaru's