Graphics. Everything else is a pittance and mostly the wrong answer. When people say "browsers" they're also wrong, because a more accurate answer is "browser

Graphics. Everything else is a pittance and mostly the wrong answer. When people say "browsers" they're also wrong, because a more accurate answer is "browser compositors." The backing layers for windows currently open on your operating system are orders of magnitude larger in size than entire operating systems, multiple times, actively running in memory by comparison. So, I think that's the real answer. Everything else seems like a pittance until you're doing some desktop computing or web browsing that requires large data structures. The two largest and most compute expensive processes running on the system you're using to read this post are probably your OS's window server, and the browser to read HN, and that's because your browser is largely also managing its own compositing system. That's why.