This might be a bug as far as im conserned:

You can disable tech trading. And because of this option ive found the AI rather "dumb", not having many techs. And in one of my previous techs the AI didnt build anything on their plants... If they did it was very little.

As for me im a scientist! I Have a race bonus of 20% (i think) and an additional bonus of 30%, and my party is Technologists. So i have an advantage (not over everyone, some has research bonuses aswell. And if im not wrong some races should have a "good research skill".)

The settings at set to Challeging and on tough.

Im Technology advanced in my current game and is advancing all the time in everything. Yet the Drath Legion declared war when they were feeling threatend by me. So i lost one planet and researched my weapons & defenses. I immidietly gained to upper hand. Since then the AI havnt made any progress at all. While i under the time at war gained several techs (through research), colonised 5 planets, became allied two 2 races.

I spyed in 2 other races that were rather close to me (aka "border" threatening" races). These was as the Drath, not many tiles build on. And no very advanced tech research.

I think when this option wasnt there one AI went in a certain direction and another in an another direction. Then they traded their techs and thus becoming "advanced"