Not going to respond to the whole thread, but a few comments:
Lag do to map size: Irrelevant for the most part. One exception is if you dont have enough free RAM and the extra map size is forcing it to page crap in and out. EotA is really heavy on memory usage in general on that note.
Lag do to creeps: The bulk of the problem. Kedge, Candle, and Gloom were meant to partly adress this issue, and from what i've seen they do (although Kedge and Candle can get brutal if you're video card is really bad). This is partly due to bad planning, but at the same time Iwas going for a very specific feel for armies and I don't think numbers could be reduced at all while retaining that feel.
Lag to triggers: Some. Majority of this problem is the amount of triggers being run non stop, although certain spells cause lag spikes (this was mostly fixed in 1.11, afaik).
Regarding me not wnating to change certain parts: This is either due to a massive amount of time requriing something ot be changed (the item system is a perfect example of that), or me being afraid to really fuck up balance (creep sizes is an example of that). Most sections of code are very self contained, so unless something causes a memory leak its not potentialy really bad. Admittedly, I have seen a few instances of really unexpected consequences...
DarnYak