Chip interconnect is much slower than that over long distances. In addition to the LC delay you mention, the RC delay is substantial and increases as the square

Chip interconnect is much slower than that over long distances. In addition to the LC delay you mention, the RC delay is substantial and increases as the square of distance so it dominates for long wires. The distance-squared effect is mitigated by adding repeaters along the way, but they add their own delay. Overall wire speeds of 40 ps / mm are typical, about 8% of the speed of light.