Marketpress slowed down my site and ate up my memory

Hi,

I added Marketpress to my Muti-site/buddypress site with 9,263 members.

Unfortuantely, this made the site unbelievably slow. Once I deactivated Marketpress, the site sped back up again. I reviewed my Marketpress settings and made sure the plugin was only available
to supporters and was not auto-activated.

Are there any other settings I can change maintain site speed - with Marketpress activated?

Here's my site:
http://networkingpeople.biz

Thanks,
Derek