hi barak - the timing on the tech tree is not perfect, and never will be. you will find that if you are an active explorer/trader, you can accelerate the global tech pace through active trading with the AIs and reach industrial age quite early.
On the other hand if you turtle and build towards a cultural victory, your lack of trade catalysing will stagnate the world and the most advanced AI will be in the middle ages into the late 20th century.
generally speaking, most games balance pretty close to historical accuracy, with the average being near spot on.
EW