[kees99]

Gold-plating of contact surface of electric connectors is indeed genuinely useful, on account of preventing contact oxidation.

Assuming good contact in connector(s) is achieved, gold-plating does not further help with high-speed signals. What matters here - is wire/cable itself, specifically, tight control over where conductors are relative to each other and insulation, so that impedance is well matched throughout, cross-talk is minimized, etc, etc...