Note that when using sass (Dart Sass), synchronous compilation is twice as fast as asynchronous compilation by default, due to the overhead of asynchronous callbacks.

The reason why we don't just create a real DOM tree is that creating DOM nodes and reading the node properties is an expensive operation which is what we are trying to avoid.

Parsing HTML has significant overhead. Being able to parse HTML statically, ahead of time can speed up rendering to be about twice as fast.

But is overhead always bad? I believe no — otherwise Svelte maintainers would have to write their compiler in Rust or C, because garbage collector is a single biggest overhead of JavaScript.

Forwarding events from the native element through the wrapper element comes with a cost, so to avoid adding extra event handlers only a few are forwarded. For all elements except <br> and <hr>, on:focus, on:blur, on:keypress, and on:click are forwarded. For audio and video, on:pause and on:play are also forwarded.

Our approach strikes a balance between privacy, computation overhead, and network latency. While single-party private information retrieval (PIR) and 1-out-of-N oblivious transfer solve some of our requirements, the communication overhead involved for a database of over 4 billion records is presently intractable. Alternatively, k-party PIR and hardware enclaves present efficient alternatives, but they require user trust in schemes that are not widely deployed yet in practice. For k-party PIR, there is a risk of collusion; for enclaves, there is a risk of hardware vulnerabilities and side-channels.