Dominic Gannaway

For prod: Svelte 5:  Svelte 4:  I don't see anything here that stands out as problematic?

I do see this in Svelte 5, which doesn't look like something Svelte 5 has in its runtime:  This is what is adding the...

@gtm-nayan It is in both, it just seems to majorly affect Svelte 5 compared to Svelte 4. Not sure why.

Interestingly, avoiding using document fragments internally from doing this: ```svelte {#each {length: 50000} as _} {/each} ``` Has a noticeable impact on performance for Svelte 5.

@gtm-nayan You're on to something: Svelte 5 logs of DOM mutations: ``` (2) [MutationRecord, MutationRecord] ``` Svelte 4 logs of DOM mutations: ``` (200019) [MutationRecord, MutationRecord, MutationRecord, MutationRecord, MutationRecord, MutationRecord,...

Ah maybe it's not that on reflection. It seems we early return and don't add the mutation observer at all.

Can you update to the latest version of Svelte 5? This should include some improvements.

@mheinzerling Yeah I think we need a better example. For me Svelte 5 is faster in script time and parse html/css time than Svelte 4.

I'm running on Chrome v124.

If you open the dev tools and enable pause on exception, it should stop on the error that occurs that is causing the hydration error. Can you show what that...