Thoughts: This looks and sounds like a system problem.
(1) Can I assume that the ClearType software is enabled in your Asus laptop? It looks like it is enabled.
(2) What browser are you using?
(3) Are you zooming either text or images and text larger than "normal"? If so, how much?
(4) You mentioned fonts that are set to 3.5em or larger being reasonably OK, so are you zooming the text in your browser to achieve that size? Where did you come up with that number? Just a way of describing "about how big"?
(5) 3.5em is quite massive. It suggests that your video card is set to a value that is less than your screen density (dpi). What is the dpi setting of your video card?
(6) If 96dpi or so, it probably should be much higher. It should at least match the dpi of the screen so the images and text are rendered at a "normal" size before zooming. It can be greater than than the dpi of the screen, but should not be less than.
For example, some video cards are optimized to scale very well at certain (common) screen densities, but become a little jagged at other densities. You'll have to see what densities your card is optimized for.
(7) Have you tweaked the setting of the video card since the computer was new? Maybe I should ask if you bought it new.
If all else fails, I would recommend returning to basic sytem defaults and reevaluating how fonts render. Something looks out of kilter and (at the risk of stereotyping) gamers are notorious tweakers .
This is not a CSS problem. The moddies might want to move this thread to a more appropriate forum as I believe this is a hardware/system issue.