[Tilecache] Quick panning with overlays

[Ivan Grcic]

HI all,

maybe the right question would be: And how many overlay layers do you
have Yves?

I remember one OL user was complaining about speed, and he had like 80
layers :D Keeping it under 3 layers at a time should do the trick i
think. People should take more care with number of layers. Instead of
piling up the layers, one should group layers in wms request: you
loose some speed on rendering it, but if you use caching its well
worth it ;) And your browser and bandwith will also be happier ;)

Cheers,
Ivan

On Tue, Nov 25, 2008 at 11:30 PM, Christopher Schmidt
<crschmidt at metacarta.com> wrote:
> 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
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-- 
Ivan Grcic