Super slow browsing on rMBP until reboot
That menu bar looks like you're on Mavericks. You should upgrade to Yosemite and see if that helps.

Speaking of which, if you haven't already, you should check how Internet-using apps that aren't web browsers perform, such as seeing how long it takes Dropbox to download a new file.

If all else fails, you should go to a place with a newer router and see if anything improves.