V1.29 changed the tech progression rate so that the AI tech rate on every difficulty level is equal. What is now changed is the Human tech rate progression and it is multiplied by a number that is 10 divided by the AI cost advantage that you will find in the editor.
So on Regent things are still equal, but on Warlord the human takes about 8 turns to research things that would take the AI 10 turns. On Chieftian its almost ********, in that the human research cost is cut in half. On Diety level it takes the human 16.7 turns to research the same tech as the AI can research in 10 turns.
Trading techs is also further distorted in V1.29 and the AI seems to demand a 35% to 50% bounty for any tech trade for a leading edge technolgy.
All things being equal, games on the higher difficulty levels that rely on technolgy instead of all out maiming of your opponent will take 40% to 50% longer than the simpler levels.