TCP window scaling, or zomg the Internet works for me again
Sites such as aircanada.com, pcfinancial.ca, and (horror of horrors!) torontopubliclibrary.ca had gotten _unbearably_ slow on Linux.
Here’s how I fixed it (as root):
echo 0 > /proc/sys/net/ipv4/tcp_window_scaling
I love you, Ubuntu forums.