[michigander]

the image will load faster if both are included.

I don't think that is the case.
The image will load as fast as it loads regardless.
However, this thread will load faster if the h/w numbers are included as it will allow the browser to pre-allocate that much space for the image within a reply.

[jellybean]

However, this thread will load faster if the h/w numbers are included as it will allow the browser to pre-allocate that much space for the image within a reply.

Okay, thanks! That's what I meant, but stated it wrongly.

Am I correct that just giving one dimension will slow down the browser (however slightly) as it tries to determine the space allocation? Probably not noticeably in most instances.