With Thymer we really care about performance, but Thymer is also end-to-end encrypted because we don't want to compromise on privacy. And it's real-time collaborative and offline first.
Thymer has optional self-hosting. Then you can upgrade (or not) at your own leisure, or intentionally stick to an older version you like better. Enshittification is a big problem in our industry. We've all been burned by it -- we certainly have -- and being able to opt out of a "new and improved!" version is a real feature.
Thymer will also be very extensible. Today we launched our plugin SDK: https://thymer.com/plugins and https://github.com/thymerapp/thymer-plugin-sdk/ with a bunch of examples. With Thymer you will be able to "vibe code" the very simple plugins and with VSCode/Cursor you can make more complex plugins with hot-reload.
What does a document system need? A few simple indexes that track links and backlinks, mentions, and hashtags. You’re broadcasting change notifications anyway (for reactive DOM updates), so updating the indexes for those manually isn’t much extra work. You apply updates eagerly and then notify other users so they can apply the same updates, with some rules to guarantee that all users end up with the same state regardless of the order in which they receive the updates. But a relational database doesn’t help with any of this. Document systems tend to be versioned, so every user action turns into another entry in a transaction log. Even queries like “last Monday’s version of my document” don’t map naturally to SQL. You can query for transactions in a given time period, but unless you have snapshots, you’re still forced to re-apply transactions all the way from t=0 if you want to re-create the document state at a given date.