How can I make my maps run faster (on Mapserver)?

Some tips on improving performance.

There are a lot of different approaches to improving the performance of your maps, aside from the obvious and expensive step of buying faster hardware. Here are links to some individual howtos for various optimizations.

• Tuning your mapfile for performance
• Optimizing the performance of vector data sources
• Optimizing the performance of raster data sources
• Tileindexes for mosaicing and performance

Some general tips for all cases:

• First ands foremost is hardware. An extra GB of RAM will give your map performance increases beyond anything you're likely to achieve by tweaking your data. With the price of RAM these days, it's cheap and easy to speed up every map with one inexpensive upgrade.
• Use the scientific method. Change one thing at a time, and see what effect it had. Try disabling all layers and enabling them one at a time until you discover which layer is being problematic.
• You can use the shp2img program to time your results. This runs from the command line and draws an image of your entire map. Since it's run from the command line, it is immune to net lag and will give more consistent measurements that your web browser.