sry whats mantis 
i wonder that there is so a big differencs between my multiplayer and singleplayer game cause all are the same stats only 50% more handicap in singleplayer and comparing the multi save is around 6 hours longer by played but there are only 35k ships oO ^^
i would be understand where the 64k ships should be ^^ what a pitty that this cause carshes ^^ but thats the think ... on my hand i dont need tonns of ships i cannt see or which arend direct represent for me at the next planets ...
so here an idea ... issnt there a possibility of an direct spawn of an adequat enemy fleet on only these planets where are attacks are possiple i mean these 64k enemy ships in my save are extremly unusefully at this moment at point ... around 10k are on the netral planet and not more than 5k on the next enemy planet ... than there are around 35-40k enemys which are unused at this moment cause they are not in danger by me ...
so all these unused ships should could be in "mind" at where they are and spawn only if there are a danger around there planets ...
issnt it a start of an idea of handle the ai ships in other way so much ships cause only memory crashes and arent in use 
my normal method is to go from planet to planet and take them ... i dont fly with an fleet 35 planets across without killem ...
and for players who handle this it works too if only the enemy ships are spawn on these planets which are next to danger / next to an planet where the human go the first time ...
please think about if there would be an possibility of having new idea on changing the method of handling these much enemy ships cause 40k are unused for this moment at my example save ^^
Mantis is the suggestion and bug tracker. It can be found at
http://www.arcengames.com/mantisbt/Sadly, it does not use your forum account information; you will need to create a new account for it. You should be able to use the same user-name and password as you do for your forum account though.
Anyways, about the unused ship thing. There are already several measures in place to have the AI use some of their excess ships. Once a planet it reinforced "enough", the AI will send some of its excess defenders to attack you (this is called border aggression). There is also the barracks and the carrier mechanics (which saves memory, because they don't store full fledged ships, just ship types and counts).
There are also cross planet attacks, where the AI sends a bunch of previously defending ships to go attack your planets, and the rarely seen scrap waves (I'm not really sure how those work or where they get the ships from).
Thus, the AI has plenty of tools to put "remote unused ships" to use.
However, the AI won't try to send those "freed defenders" through the wormhole to attack until it is confident that it has a reasonable chance to win that battle. Thanks to the absurd number of ships you have on your bottleneck planet (in your single player game), it will take a similarly absurd number of ships from the AI before it decides to go in.
Plus, those "waiting" ships only total to 10000 ships, or about 1/6 of the ships the AI has. I'm not sure why border aggression isn't kicking in more. Or for that matter, why aren't carriers being created more.
One last thing, about your multi-player size question. The memory limits can be hit in multi-player a little faster because if there are two players, the AI is slightly less than twice as strong, so it can still put up a fight. This would imply getting around twice as many ships, thus hitting memory problems earlier.
Sorry for the long posts, but answering your questions required going over a lot of information.
