[Tilecache] Quick panning with overlays

[Christopher Schmidt]

On Tue, Nov 25, 2008 at 11:22:06PM +0100, Fredrik Lundh wrote:
> Yves Moisan wrote:
> 
> >> perhaps you're not using a different set of DNS hostnames for your
> >> overlays? If so, do that
> >
> > I remember seeing that, but I dont' know where.  If you have a pointer
> > nearby, I'd appreciate it.
> >
> >> -- they will then load completely in parallel
> >> to your baselayers. (Also, I hope you're using the multiple-DNS trick,
> >> as that will cause a much faster visible loading time to the user...)
> >
> > Same as above :-(
> 
> These are standard HTTP optimization tricks, and are not specific to
> TC in any way.  See this article for more details:
> 
>     http://yuiblog.com/blog/2007/04/11/performance-research-part-4/

And for OpenLayers specifically:

  http://openlayers.org/dev/examples/multiserver.html

This only has a base layer -- I would recommend using one set of
hostnames for base layers, and one for overlays (2 and 2 would make four
total). 

Another optimization technique is to limit the buffer:

  http://dev.openlayers.org/apidocs/files/OpenLayers/Layer/Grid-js.html#OpenLayers.Layer.Grid.buffer

Setting it to 0 would result in the minimum.  

Regards,
-- 
Christopher Schmidt
MetaCarta