The main performance gotcha to watch out for with hand rolled DOM manipulation is causing a reflow. Pretty much if you make changes to a DOM element and then r

The main performance gotcha to watch out for with hand rolled DOM manipulation is causing a reflow. Pretty much if you make changes to a DOM element and then read a computed value from it before a new frame renders (like dimensions etc), the browser has to recalculate the page layout before it can return an answer. Fast: Read -> Modify -> Paint Slow: Modify -> Read (reflow!) -> Paint This generally isn’t an issue but if you’re seeing hiccups it’s either GC run wild, synchronous code chewing up the frame budget or frequent reflows.