This is a warning that if you added new units or changed attributes the AI will not take advantage of these changes. (like if you added range fire to IN it would not use that - or if you added a "flame Thrower" it would never build one)
Viewing post in AI player not optimized!
What this is telling you is that the Player Type (Expanding AI, Enhanced AI, etc.) does not have a correctly matched script. Since you have a mismatch here, the computer will play at a Classic AI level. It doesn't mean that your opponents will play like dead bugs. Of course, you could argue that the Classic AI does play like dead bugs. :)