[mapserver-users] Using Fast CGI with MapServer to alleviate poor performance

[Christopher Schmidt]

On Thu, Sep 18, 2008 at 08:59:51PM +0100, John Westwood wrote:
> Hi Paul and other MapServer Gurus,
> 
> I have discovered a huge speed increase by using OpenLayers.MapServer (native) layers instead of OpenLayers.WMS layers. It is about ten times faster, I do not exaggerate. Why is WMS so slow? I have read that MapServer is a fast WMS server, have I done something wrong for it not to be?
> 
> What do you think could be the problem?
> 
> I will give it some thought tomorrow.

Is it possible the difference is 'projections'?

The Layer.MapServer in OpenLayers does not include any projection
information, so if you have your OpenLayers Map configured in a way that
would (via WMS) cause MapServer to reproject on the fly, it will have
significantly different performance. (There are other side effects if
your projections are actually different, but they might not be noticable
at a first pass.)

I agree with Steve that it probably makes sense to generate:

 * A WMS-served URL
 * A MapServer-served URL
 * Your mapfile configuration

Those three things will probably help point towards the misconfiguration
in your current setup.

Regards,
-- 
Christopher Schmidt
MetaCarta