I'm not comparing against Angular (which in v1 is known not to be super fast) just between browsers. I was mainly looking at https://vaadin.github.io/gwt-polym

I'm not comparing against Angular (which in v1 is known not to be super fast) just between browsers. I was mainly looking at https://vaadin.github.io/gwt-polymer-elements/demo/#gwt/JavaApiWidget https://vaadin.github.io/gwt-polymer-elements/demo/#gwt/Java... . It uses a lot of widgets on one page. Take a look how on loads in Chrome, Firefox, Edge (refresh to minimize network effects). I didn't go really deep in it, but first look was that lots of time was used in registering custom elements. Sure, here it is wrapped in GWT (which would be my case), but it doesn't seem to add much, rather the fact it loads all widgets from Polymer.