The gather rate of rare resources can be increased in various ways, as described in the main article.
The decrease in production times can be quite significant, especially when playing a more combat-oriented game, effectively allowing you to field five units in the regular time of four. Most infantry has a regular base production time of ~15 seconds per unit, thus is created at least (see below) 3 seconds faster. Cavalry units (regularly 15–20 seconds) gets a decrease by 3–4 seconds, ships (regular 12–24 seconds) by 2.5–5 seconds. Note, that production times for combat units ramp up (like resource cost) with each unit of the same type the nation already has. Also, a Cotton resource near the starting location offers a good way to boost initial Timber production and to compensate the lack of Timber on some map styles (Great Sahara, African Watering Hole, etc).