Why is the Harber process performed at higher temperatures rather than low?

The forward reaction in the Harber process is exothermic. Following Le Chatelier's principle, the reaction would therefore be favoured by using lower temperatures, increasing the yield of ammonia at equilibrium. However, decreasing the temperature would lower the rate of reaction, slowing the production of ammonia. Therefore a higher compromise temperature is used to make the production of ammonia feasible; low enough to obtain a good yield of ammonia but high enough to maintain a reasonable rate of reaction.