title: Recommendation On Data Store For Website's User Activity Log
body: <p>I am looking for some recommendations on a good data store for activity feeds. The goal is to have a Twitter/Facebook type feed log consisting of various activities users can do throughout our website. The "wall" or "feed" would updated via AJAX showing what the users of the website are currently doing. It will be written to often and then the most recent will be displayed on the site.
  (e.g. John Smith recommended Jane Smith's article 2 seconds ago)</p>
  
  <p>We currently are storing the feeds in MySQL but performance has been poor and I'm concerned with hindering performance throughout the rest of the website if we are constantly hitting the database to grab the most recent user activity as well as writing the feeds.</p>
  
  <p>Any recommendations would be greatly appreciated!</p>