Calculating remote loading time

hi to everybody. This is my first post
First of all: excuse me if I'll wrong something but I'm italian.

Now my "problem". Is there a software or Firefox addon to calculate the loading time of a page from remote even if the site stays in local?
Let me explain you better: I already use Firebug and its fantastic extensions to check loading time (and much other) of my local site but I'd want to calculate the remote loading time even if the site is on local.
For exemple a math formula in witch there are connection speed size of the page and server distance (i'm supposing of course.)

I ask it because I remember that there is a similar function in Dreamweaver but now I use PSPad (and Firebug for debagging)

Thanks in advance for your help.