Installed a Firefox add-on called "Tab Memory Usage"
Memory usage with the same content: (loading the page, don't do anything else
old: 4m
new: 31m.
The new Autosport version is in this regard the opposite of mobile friendly.
Regards
A larger file size is to be expected - the old version of Live had mostly text with a few images while the new version has far more images as well as other embedded content such as Tweets, etc.
We're serving different sized images on mobile and desktop. If those figures were pulled out from Firefox on the desktop, then you're seeing a much larger file size for the new Live than anyone should be loading on mobile. Additionally, there is an option to switch to text updates only (ignoring our images and any embeds which support images or other high bandwidth media). If anyone is struggling with file sizes on mobile, I'd recommend that you use Live with this turned on.
We've tested the new version of Live on a number of different devices and we're actually pretty happy with the results and the loading speed. My own phone is a model which came out in 2013, but it can load a whole page of live from the Barcelona tests (with nine hours of coverage and updates including images) without any trouble.