When Mapnik is processing layers, it tries to clip the map bbox to the
layer extent... unfortunately it doesn't test for intersection first,
so the "clipped" bbox is completely bogus. The layer is then asked for
features for this bbox, and if you have a lot of small raster layers
then this has a big performance impact.
I've attached a patch that fixes this, and also returns something
slightly more sensible from Envelope.intersects in the same situation.
[randomjunk] sorry, can't attach patch properly...
expected integer, got u'1048576 # 1MB'
--- include/mapnik/feature_style_processor.hpp (revision 729)
+++ include/mapnik/feature_style_processor.hpp (working copy)
@@ -123,6 +123,12 @@
// back project layers extent into main map projection
[artem] Applied, thanks!
[springmeyer] will appear in the 0.6.0 release, so back-assigning to 0.6.0 milestone.