Midori.
My browser of choice used to be Google Chrome, but the latest versions have become resource hogs, and I was feeling this on my older machines. I decided to take a look at alternative browsers and settled on Midori.
I turned off JavaScript (the best JS is dead JS), enabled ad blocking, and customized keyboard shortcuts (changing Ctrl-F to Ctrl-S as in Emacs). It loads noticeably faster, and I can’t even tell how many tabs are open while using other applications.
If you’re using Linux, it’s likely in your distribution’s repository. If you’re on Windows, the Midori home page provides both installable and portable packages.