Clustering the markers will greatly improve performance: http://google-maps-utility-library-v3.googlecode.com/svn/tru...

I actually had this same idea a few months back. I'm the developer of truxmap.com, a real-time food truck map, and I wanted to export the concept to farmers markets. However, the USDA data set isn't sufficient because it doesn't include days of the week and times. Nevertheless a map i easier to read than a table.