All other things equal, higher bandwidth links are inherently lower latency.

Propagation delay usually dominates latency, so it's generally not the biggest factor, but on a simple local network with two PCs and a switch, you can expect about 1ms latency with 100BASE-T, and 0.12ms latency with 1000BASE-T.

  | Component                                      | 100 Mb/s            | 1 Gb/s            |
  | ---------------------------------------------- | ------------------- | ----------------- |
  | Propagation (30 m)                             | ≈ 0.15 µs           | same              |
  | Two NIC serializations (TX + RX, 1 500 B each) | 2 × 120 µs = 240 µs | 2 × 12 µs = 24 µs |
  | Two switch serializations (store‑and‑forward)  | 2 × 120 µs = 240 µs | 24 µs             |
  | Processing in switch + NICs                    | \~10 µs             | \~10 µs           |
  | **One‑way latency**                            | **≈ 490 µs**        | **≈ 58 µs**       |
  | **Ping RTT** (×2)                              | **≈ 1 ms**          | **≈ 0.12 ms**     |