I have a community news site that has alot of newslinks,

I have a community news site that has alot of newslinks, images and plugins.
The plugins out there for business directory and classifieds are heavy and seem to add to decreased page speed. I have been working on optimization for weeks now and can't get my page speed under 5. So I would like to incorporate two additional sites using a directory and a classified theme but would like the option of being able to pull posts (ie. latest classifieds, latest directory listings, etc.) in the form of a sidebar widget on the main news site. Is this something that multisite will enable me to achieve?
Thanks
Anna