I've noticed a few designers discussing on Twitter about the role of font smoothing. I thought of consolidating the discussion here such that it can later be used as a reference.

The linked blog post advocates the nonuse of font smoothing. Agree or disagree?

We should never use custom font smoothing imho. Choosing the text rendering method is an OS and user specific preference.

This should also be considered from a performance angle. Font smoothing on large amounts of text requires more CPU. I’ve run into sites that do this, and scrolling through them is an awful experience.

At times, they’ve brought me to the brink, and I’ve found myself manually removing the font-smoothing declaration with the inspector.

“Font smoothing on large amounts of text requires more CPU”

Are you talking about sub-pixel antialiasing (-webkit-font-smoothing: subpixel-antialiased;) or standard antialiasing (-webkit-font-smoothing: antialiased;)? Sub-pixel antialiasing requires more CPU than standard antialiasing.

Sub-pixel antialiasing is not possible in a lot of situations:

• iOS doesn't use sub-pixel antialiasing anywhere, because the display orientation changes, and the sub-pixel order and orientation changes with it. That breaks the trick to gain extra resolution.

• Sub-pixel antialiasing typically requires an opaque background to be composited on.

• Sub-pixel antialiasing is less important on high DPI displays.

Further discussion: iOS and Android don't have sub-pixel antialiased type. Microsoft's Surface doesn't seem to either (I haven't seen any screenshots of Windows 8's Metro UI with it). So the entire future of mainstream computing is going to be high DPI, but possibly not contain sub-pixel antialiased type.

If you're grumpy about things not being sub-pixel antialiased, the future is looking pretty bleak.

My advice: Move on.

This battle has been fought and won. Faster performance and devices that can be used sideways and upside down trump slightly better text rendering.

Standard antialiasing. I can’t imagine sub-pixel antialiasing.

Actually, the default IS sub-pixel antialiasing. The former takes up more CPU.

Is not antialiasing at all on the cards? Seems like something no one would want, except as a pixel art effect.

I'm not sure of the performance hit for standard vs sub-pixel antialiasing, but I'd assume it'd be roughly 3×, as there's three channels of rendering an compositing verses one. I'd love to hear from a type-rendering engineer on the topic though.

“The former takes up more CPU” — What makes you think sub-pixel antialiasing is faster than standard antialiasing? There's more work being done with sub-pixel antialiasing.

I don’t see how it would, but spreading -webkit-font-smoothing: antialiased; over large amounts of text seems to degrade scrolling.

I general, I do not use the setting at all. Some icon fonts displayed small, around 12 pixels, can benefit from the antialiased setting, though.

I hear everyones point regarding static tupe, but antialiased is essential when you use any type of CSS transition, transform, or animation. When WebKit does any of that, it switches type in the animated element to antialiased, causing a disgusting flicker of text. I'd rather have it antialiased by default in those cases and have different type looks than that horrid flash.

@Julius: Absolutely. And this is why it's good that the designer of the website or app can decide which method to use, based on what's important for that page. Also, text in SVGs is rendered without sub-pixel antialiasing (Safari/OS X).

There's many situations where sub-pixel antialiasing simply isn't possible. So you have to decide: Inconsistency, animation with flashing and colour fringing... or slightly improved legibility.

I wrote some thoughts on the topic: bjango.com

The bottom line is that sub-pixel text rendering is on its way out. My guess is that it'll be mostly gone from mainstream computing within 5 years, or at the very least, far, far less relevant.