First, I'd like to let it be known that this is my first journey into developing mapping applications with such a large set of data. So, I am in way locked into the techniques or technologies listed below...
The Overview
What I am trying to accomplish is the ability to load my company's market information for the United States onto some form of web-based mapping software. Currently I am trying to accomplish this with Google Maps JS api and GeoJSON data, but am not against other alternatives. There are roughly 163 files (ranging from 6MB to 200KB) that I have exported from ArcGIS into GeoJSON files, and then loaded into a database (currently as GeoJSON strings). We have developed a UI that loads the data based on the current map bounds and Max/Min calculations in the corresponding records.
The problem I'm running into is the render time on the map itself, which is annoying when switching between different regions, states, or zoom levels. The API calls to load the data are acceptable in regards to the size of the data being retrieved. My boss said it is great for a proof of concept, but would like to see it much, much faster.
The Questions
What suggestions could you offer to increase the render time?
Are there better options (3rd party libs, techniques, etc) for what I'm trying to accomplish?
It was suggested by a co-worker to export the map shapes and just use the images for overlaying the information based on the coords. Any input on this?
One solution to your problem could be reducing number of vertices in polygon or polyline layers (files) while preserving feature's shape. In that way geoJSON file would be smaller and easier to render. You can use tools available in ArcGIS for Desktop. See How to Simplify Line or Polygon or Simplify Polygon
I'm sure there are similar tools in QGIS or any other open source GIS software.
There are other solutions to your problem like prerendering data in map tiles that could be overlayed over Google Maps basemap(s). That is probably the fastest solution but more complicated. Maybe this could be good starting point.
Just couple of random thoughts. On one project I worked on I noticed terrible performance with geoJson I loaded via REST service. I found out that browser's JavaScript engine had hard time parsing large geoJson responses. I finally decided to load data in batches (multiple requests). Performance increased enormously.
I noticed you use 163 files (layers?). Do you display them at the same time (no no no) or you have some control panel to switch layers on/off? If you display them at the same time then performance will suffer for sure and you should look into generating map tiles with thematically grouped layers. In that way you'd come up with couple of tile layers that you can switch on and off.
Also, if data used to generate tiles changes frequently than tiles aren't good idea. Then maybe you should look into Web Map Services. WMS generates maps on the fly from data stored in database. GeoServer supports WMS and it's easy to configure and use.