Yes, it's infinite velocity. When you compute an amplitude from a Feynman diagram, you sum (integrate) over intermediate particle paths that are superluminal. The math is structured in a way that these contributions cannot actually be used to send signals, but the contributions are crucial and cannot be discarded. Essentially, they represent the relativistic generalization of the effect where one particle in a Bell pair "influences" another over a spacelike separation, but in a subtle and spooky way that cannot produce superluminal signaling.