Ok, I've come up with something that works too well in crippling AI research rate. I was playing a game (I am about to win) where I was neck and neck with the French in overall power until I booted the Japanese and became more powerful. Anyway, It is the modern age and I had to find a way to mess up the French research and production rate before they had a chance to become a runaway AI. So here's what I did. I checked my military advisor and found to my surprise that France was a Republic! They had recently signed a MPP with Zulus who were adjacent to the Japanese. It was the perfect chance to declare war on the Japanese and get the Zulus (much weaker and would accept something pretty cheap) for a military alliance versus Japan. Then I would get France into the war for ZERO gold! So the first part of this was done. Then I knew from experience that a civ at war stays at war much longer when it loses a city to the enemy so I kept giving France cities that I took from the Japanese which would be empty and the Japanese would retake the next turn! This would accumulate France's war weariness and caused them to lag way behind me in research and production! It is perfect but I admit, it is almost too effective to be a good game strategy.