function() { Array.prototype.slice.call(document.querySelectorAll('[data-reactid]')).forEach(function(element) { element.style.background = 'rgba(255,0,0,0.1)'; }) }

is executed every 500 ms using command in question. So if the above function takes 500 ms or more to execute, the tab will get stuck (I would think).

Try just executing this command once:

    Array.prototype.slice.call(document.querySelectorAll('[data-reactid]')).forEach(function(element) { element.style.background = 'rgba(255,0,0,0.1)'; })