Safari and upload speed are not correct per my ISP

Ok so this is not exactly the most pressing issue of the day, but I'm still looking for a explanation and perhaps others are too, so...

I am getting the correct download speed in Safari (Version 8.0.3 [10600.3.18]), but I am not getting the correct upload speed. I have confirmed with my ISP that I am setup correctly from their end, they came out checked their hardware, etc. To prove that point, I have downloaded Firefox and it does get the correct download and upload speeds. Plus I have tested in Internet Explorer on my Windows virtual machine and it too has the correct download and upload speeds. Since two other browsers utilizing the same hardware and presumably network settings, one on the Mac side and one in the virtual Windows side, have the correct results, then the issue appears to be with Safari. The questions is what in Safari is causing a throttling of my upload speeds?

Like I said not the most pressing issue as I can just use Firefox and problem solved. Sort of, I'd still like to figure out why Safari can't manage the speeds that the other two browsers can. Oh and I have made sure all the current updates are installed, restarted the Mac, the entire network setup, etc. just to be sure.

Thanks.