Too many markers: how to render them server-sided as a tile layer?

I'm developing a web-app for public transportation info using Google Maps JavaScript API V.3 as front-end. But due to high number of markers (transit stations) displayed on the maps, the client-side performance is quite poor, especially map panning (despite markers being dynamically loaded based on map boundary). For usability design, clustering markers is not an option. So I am considering rendering these markers as a separate tile layer on server-side. Then maybe using google maps event onclick and onmousemove on map object to imitate marker interaction. The question is: what is a good approach to do this? Which service/API/software/server should I look into that can accomplish this with minimal overhead and learning curve? Could you please point me to the starting point? I have checked out Google's Fusion Table, but it doesn't allowed custom marker image, therefor not an acceptable alternative. My project environment is: PHP CodeIgniter on Apache server as back-end, PostgreSQL 9.2 + PostGis 2.0 as database system, all hosted on an Amazon EC2 small instance server. PS. My website is at www.bussup.com , in case you're interested (it's yet to be internationalized so sorry for no English support)