I've also noticed that disabling JavaScript has a huge effect on some websites' speed. But other sites don't even work without it nowadays.
I override all web fonts, I just want to use a readable one. There's a noticable trend with embedding icons in fonts. Yahoo mail uses them. This doesn't feel quite right, even if it is a neat hack, and it can be annoying.
How I view Yahoo mail: http://postimg.org/image/unnwg0d9p/
Google use a lot of buttons without text, using icons instead, which a lot of the time are background images. This lends to a lot of mystery meat navigation. Google+ is a bit of nightmare on that front for me.
I don't think my setup is that exotic, all I'm doing is trying to use consistent background and foreground colours, font and text size.
It's amazing how many sites seem to gloss over accessibility.
An instagram page: http://instagram.com/p/ieluJhv-V7/
How it looks to me: http://postimg.org/image/an1jbvf65/
Yup, pretty useless. I've never been able to use/see Instagram pictures without flipping between browsers!
I really like typography (calligraphy has been one of my favourite pastimes for many years) but I think its implementation on the Internet is very bad from a usability perspective.
(I suppose you may get web page layouts "jumping" if the downloaded font had very different spacing to the fallback font. EDIT: Ah, just learnt this is called FOUT. http://www.paulirish.com/2009/fighting-the-font-face-fout/ Still, I'd personally prefer FOUT to being unable to read the page.)