“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.