Does picture size matter when attaching to a post?

I'm old fashioned and use an actual digital camera to take pictures.  Then I upload them from my computer to my posts.  The pictures are about 6MB.  I usually shrink them before uploading to Permies but that takes a few steps.  Does Permies.com automatically shrink photos to the ideal size and therefor I'm wasting time?  If not, what's the ideal size for a photo when attaching?

Thanks!  

Theres a thread, about it  but i think the widest should be no bigger than 700. The site doesnt do it for you.

Cool, thanks Wayne!