Super slow browsing on rMBP until reboot
Solution 1:
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.