techs

Hey, I need some advice here. In my second game on emperor I had a six tech lead in the beginning of the industrial ages, but in my third game...

...in my third game on emperor (huge map, continents, 16 civs) I ended a war with Iroquois destroying Salamanca and, along with them, getting a two tech lead. But by the time I got Polytheism and Monarchy all the other known rivals already had those+3 other techs. That means I get 2 tech in the same time as they get 7? How does the AI manage to get them so fast??? I also found a camp from which I got Philosophy and sold it to all civs for gold, maps, communications, and two techs (map making and Code of Laws). Then i looked at their territory - the biggest city was population 5. Mine was 4. I had about the same number of cities as they did and in good spots. So what's wrong?

Tech lead on emperor? That;s very tough, especially with so many civs. The comps trade amongst themselves which makes it very hard to pull ahead. Plus on emperor the computer has production bonuses so their cities are more effective.

Thanks, that might explain it.
So I figure the only way to be ahead or at least not behind is war, and if you have lots of luxuries that can help too (sometimes trading for techs and sometimes for military help). Is that right?

And I believe war was exactly what saved me in my second game - I deleted it as it became too easy with everyone discovering destroyers and me 1 tech away from modern ages. I just crushed everyone with tanks and my battery of 15 artillery units (along with 10 infantry and 5 cavalry units I captured 5 cities in 7 turns - one of them was Salamanca with 4 wonders).