Thanks for the feedback
i took a look at the multiple snort interfaces, and they werent using all that much. There were a couple plugin processes that were using a lot, and i thought at least one had a memory leak, because when i rebooted the memory use went down. But after a couple days, same thing.
so amazon to the rescue; plugged in another 16gb which was dirt cheap, and now it is using about 31% of the 24gb, so all is well. cpu usage was never an issue (about 23% as i write this, i have seen it goes as high as 80% but thats rare and very temporary)
so im done, i have everything installed i needed (and some plugins i just wanted to play with), and it runs everything im throwing at it, so im happy.
Lucky i got this version; not sure the less powerful ones would do what i am asking.