Font smoothing issues with browsers - a long time problem
Chrome, Firefox, and Safari on Windows use the native Windows algorithm to do the smoothing, which often times leaves larger text sizes looking jagged.
However, IE uses its own font smoothing algorithm and makes larger text look a lot better, but also has the drawback of making smaller size text look too thick.
I feel like this is a problem for the longest time, and is still not fixed.
Here's some screenshots. In the first one, you can see that IE does a better job with larger fonts: "Doing good is part of our code".
But in this screenshot, IE makes smaller text look a little boldish: