after conquering enemy cities getting the populace to switch to your race

In civ 3 After conquering enemy cities ive noticed that some times it takes forever to change the nationality of the citizens from the conquered one to your race.Is there anything you can do to speed the process up? Ive tried building temples,libraries,courthouses and stocking the city with military but it seems some cities still take forever while others switch quickly. HELP thanks guys

Can't annyone post in the right forum? This is NOT the Civ 3 section of the site!