Enhance, Optimize and Bugfix Google Map API v3 Application

Under development is a Google Maps web application (Ruby on Rails and Javascript) which pulls data from a MySQL database which is updated in realtime and then updates the map with poly lines, custom icons and data overlays. The current app includes mouse hover information boxes, semi-transparent overlays and various data. The application will need to update the map as new data comes into the database which will include adding new icons and deleting older ones. There could be up to several hundred icons and polylines on the viewable map. The mapping application also includes 'playback' in which the historical map data can be played back for a user. Currently, the application is partially complete; the rendering of the map is unacceptably slow with a moderate object count and can cause browser lock-up, and the current front-end developer is no longer able to work on the project. Two other team members are a back-end developer (MySQL and Ruby) and an HTML developer. What's needed is a Javascript developer who is familiar with high-performance mapping/graphics work who can recommend techniques to increase performance and lower resource requirements though optimization. Some techniques which may be explored in the area of performance improvement include, but are not limited to: 1) isolate the icons rendered to only those in the current viewport 2) reading multiple datapoints and painting them as one overlay rather than individual overlays 3) some form of local caching scheme to reduce DB network reads 4) reduction of visual features in the application based on recommendations 5) other? The first milestone of this project is to perform immediate bugfixes for a planned demonstration later this month. The second part of the project will be to complete planned functionality in a design document (less than 50% is completed). The project will provide part-time work with occasional full-time participation required and may run through the end of the year. If the project is successful there will be follow-on development work with new functionality. The developer who is awarded this project will have a strong Javascript/mapping background, understand optimization techniques and have good communication skills and habits in order to work with 1-2 other developers to complete the project. More details and a URL to the development site will be provided before making an agreement, so I understand any bid provided here to be negotiable based on the level of effort once the scope of the work is better understood.