"Settlers are produced faster."
In-game description

Koprulu Viziers is a technology in Age of Empires III that is unique to the Ottomans and can be researched at the Mosque once Millet System is researched and the Colonial Age is reached. Once researched, it reduces the time at which Settlers are spawned from Ottoman Town Centers by 5 seconds (for a total of 10 seconds with Millet System). Abbasid Market is the further upgrade of this technology.

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