Performance regression in 0.0.16 (possibly related to bind:clientWidth?) #42

First of all, great package, I love it! :) I am using this package to render a chart in a table, and it seems to be having performance issues starting with 0.0.16. I have created [a REPL](https://svelte.dev/repl/b9dff6e521204308a8676f3fe10b2c6c?version=3.48.0) so that you can test it out. Clicking on refresh should give you some number, which is a rough and inaccurate estimate of the time it took. Now, run the same thing, but using `0.0.16`. You can see it's about 2-3 times slower in the best cases. When observing performance in the profiler, it seems to be related to style and layout recalculation. 0.0.15:  0.0.16:  Also, I noticed that some purple appeared *during* mount (which is what is causing major issues in my website): 0.0.15:  0.0.16  This looks pretty much like [layout thrashing](https://kellegous.com/j/2013/01/26/layout-performance/) caused by `bind:clientWidth` and `bind:clientHeight`, but I could be wrong here. ---- I'm guessing this is a Svelte issue, but I'm wondering if we could do a quick fix in Pancake to bring back the original performance here