image preview really slow!!!

In the latest realease of blender, the image previewing is really slow on my machine. Ive never had a problem with previous versions. Is this a known bug or do I need to change my settings (I know its changed the way it uses memory)

Image previewing - pressing ctrl when browsing for textures and using material nodes

It’s slow because it uses the renderer now. This probably should be a preference but it’s much more acurate than before.

its a thumbnail for a bitmap…why does it need to be ‘acurate’ Its only to check you’ve got the right file for the texture…?