Nvidia control panel

Should have an option to scale the image to fit full screen in your graphic card's control panel.

they're right:
go to the "Adjust desktop size and position" tab.
there, you can select "Full-screen", which means that whatever resolution you select in-game, it will get stretched to fill it all up.

and i've read that "Perform scaling on: Display" is supposed to the better-performing one, but haven't really read up on why this is supposed to be true.

Some people believe that image scaling using a monitors scaler is faster/better than GPU scaling. Depending on the GPU and/or monitor, this could be true. The opposite could be true too. Maybe neither is noticeable. If you have the choice, try both and see which one you prefer, if any.

how do i do the same on a mac?

and only 2 years ago ppl was crying coz openplugin had been banned...

stretching a resolution doesnt give you higher fov stupido

that was my point actually...

if you come to a point you stretch a resolution, it means you're using a different resolution and possibly a different ratio, if you use a 4:3 ratio resolution on a 16:9 native monitor, whether or not you stretch it you will obtain a narrower horizontal fov

but well if you stay in 16:9 ratio on a 16:9 monitor, the horizontal fov will stay the same, the only thing that would vary is the density of pixels

you can use an extreme widescreen resolution giving you a higher fov and stretch it vertically..
not that its worth crying about