So our hosting via Dreamhost was pretty bad on the shared account. Dreamhost suggested trying a free week of VPS (virtual Private server).

I do that and come to find out the advertised price of $15/month only includes 300MB of memory.
I set that and site gets restarted over and over for being over the limit.
I chat with support and they give me a credit so I can set the limit to 4GB!
Of course PHP FastCGI uses just about all the cache it can!

I slowly lowered the memory from 4GB ($200/month!) down 800MB ($40/month). I still got a bounce notification due to using too much memory.