Need Help site very slow

Hi i'm new to site building and php.  Ive been reading the heck out of everything i can to try to learn elgg but i'm still not getting everything.  My site is getting close to completion but all of a sudden started to run very slow and no one is on it except for one or 2 ppl. i'm on a vps with a soft limit of 800 mb of ram and a hard of 2 gig. I'm running virtualmin for my panel.  Maybe one of u ellg gurus could take a look for me my site is http://www.nesstream.com thx in advance for your time.  If i left out any info you need sorry i'm still new at this.