[Spunky]

"If you put in both height and width, as you say Jim recommends, then this allows your web browser to paint the screen faster, before the image is entirely downloaded, because at least it knows how much screen space to reserve for the image.

That's it. I just didn't know how to say it. :-)

[ThePythonicCow]

That's it.

Good - thanks for persisting. It led me to make sense of this common controversy.