I'm using acdsee 7.0, seems to be the best modern version of this software for me.
I noticed that xnview, irfanview or faststone displayed pictures with aliasing by default when they were bigger than screen resolution (scaledown). There is an option to soften this, but it slowdowns the viewer between pictures (acdsee 7.0 is softening pictures as well, but it is faster, to me...)
However, I'd like acdsee 7.0 to be faster, sometimes...