Pump. Recirculating (whirlpool) will cut your cool time. I have a 60' 1/2" copper whirlpool IC and with 45-50º well water I have a 1 minute half life when cooling. With 50 being the coldest I can go, I drop 75º in a minute, then another 35 or so in another minute, and so on. Takes about 15 minutes to get below 60.
I also have a SS direct fire recirculated mash tun. I get nice clear well converted wort that way, and with my camp chef on low flame it holds mash temp nicely.