Avoid recalc style.
Test editing script directly in DevTools – Chrome will update executing on the fly.
Continuous paint mode - tell Chrome to paint over and over again.
Toggle CSS in Devtools and watch what it does to performance in Timeline.
instead top: -106px
* Get all the style rules
* Evaluate the selectors and match against DOM
* Selector matching cost is here, typically \<1O% of time
* Calculate the computed style for every element
H to Hide selected elem to figure out which elements is affecting
Layout trashing = Recalc -> Layout -> Recalc -> …