uDig GIS: A First Look (Linux Journal)

For the next version of uDig you will find that raster performance is much
improved. We are upgrading from GeoTools 2.2 (which loads rasters into
memory) to GeoTools 2.6 which is leaving them on disk.

In general uDig likes to leave all the data on the disk and run light - it
is not worth loading shapefile data into memory (because that would limit
the size of data you could work with). We are very happy with the
improvements to GeoTools that enable us to take this approach with raster
data as well.

This improvement to raster support is largely due to the work of GeoTools
and the image-io-ext project. This work (while often using Java for speed)
is making use of gdal/ogr to read in some of the more exotic formats (like
MRSID).