Answer:
Interesting question. But it depends -- do you mean an African Swallow, or a European Swallow?
Actually, there are 83 species in 19 genera of the swallow, enjoying a cosmopolitan distribution across the world and breeding on ALL continents except Antarctica.
That having been written: GENERALLY, swallows and martins forage at approximately 30-40km/h and are quite capable of reaching 50-65 km/h when traveling.