Chrome browser rendering engine and JS engine

The role of the rendering engine consists of parsing the HTML generation DOM, generating a render tree, DOM changes and rearrangement under style changes (recalculation of layout position), redrawing (drawing on screen)

The rendering engine is mutually exclusive with the JS engine, but according to timeline Discovery, the re-order and parsing of HTML at JS execution may also be performed simultaneously, but redrawing must be mutually exclusive

This is probably the browser's optimization strategy, when the JS engine executes, the rendering engine will not completely do not work, but will do some recalculation of the layout and parsing the HTML things, in short, the browser loading the page as fast as possible

Chrome browser rendering engine and JS engine