High bonus gives AI five times more resources, research, inteligence and construction rate. Yet, AI does not perform much better than with say, low bonus. I always wondered why is it and I think I finally found the way to make AI to take full advantage of its bonuses.
There is a line in AI_settings.txt:
"Maximum Maintenance Percent of Revenue".
Usually it is between 80% to 98 % Obviously, it works as a sensible precaution against AI bankroting itself. BUT, AI does not "know" that it has bonus ! In calculating whether to build a new ship, it uses unmodified income, one that is displayed in empire revenues window. Thus, at high bonus, AI has full coffins but still refuses to build more ships than it would build without any bonus
IIRC, this problem has been discussed before but apparently it was not fixed by MM (I play latest Gold patch). However, I think it can be solved by setting "Maximum Maintenance Percent of Revenue" to 200% or even higher value ! When I did it, AI start to build many more ships up to maintanance cost much higher than displayed income. Of course it was still in plus territory thanks to 5X bonus.
Obviously, modding AI this way renders it unsuitable to "non-bonus" game but heck, who ever plays that way
One more thing, changing AI settings has no effect on already existing .emp files. They should be generated again after this.