I've been in the enterprise switch and router business for over 15 years. I've performed and had performed 100s of throughput, latency, and stress tests for shipping product to paying customers. Never, not once, has a poor result been blamed on a cable.
Buy a decent cat 5 cable (cable modems connect at 100Mbits which is very slow by todays standards) and forget about it.
Buy a decent cat 5 cable (cable modems connect at 100Mbits which is very slow by todays standards) and forget about it.