Resurrecting another dead thread? Yes, the materials used in any cable’s (or PCB laminate’s) dielectrics affect signal transmission speeds, according to the Dielectric Coefficient (Dk) of the material. ie: https://www.edn.com/rule-of-thumb-3-signal-speed-on-an-interconnect/ and:
https://electronics.stackexchange.com/questions/494977/signal-velocity-in-pcb-traces Feel free to argue (with those established facts).
