похоже, проблемы с перформансом у Stencil тоже есть. ну либо его надо уметь готовить
“We went on the way of writing our new UI kit in WebComponents using Stencil. We were suffering performance problems (using ~200) components on a single page, but it was reasonable. That was in Chrome but we checked Edge then. It took the site 20+ seconds to load! Upgrading to Stencil One then made it even worse. Seems like using slots is just not a thing using polyfills, it causes re-layout every time it moves an element in the DOM. After struggling for a month with it, we decided to port the kit to React components. Even solved every Chrome issues we had regarding performance.”
https://dev.to/wintercounter/comment/cmg6