Yjs/community

That would be surprising to me too! The hard drive is an SSD. Does anyone else have any data on this?

Related to this, I am using both y-websocket and y-indexeddb. The README says

y-websocket
A module that contains a simple websocket backend and a websocket client that connects to that backend. The backend can be extended to persist updates in a leveldb database.
y-indexeddb
Efficiently persists document updates to the browsers indexeddb database. The document is immediately available and only diffs need to be synced through the network provider.

from which I concluded that y-indexeddb (which uses the local client) should sync faster than y-websocket (the websocket server is in Ireland and I am in England). But I always find that the websocket provider syncs first, by a few milliseconds. Why?

The code looks like this (exactTime() yields the time now to the nearest millisecond):

    const doc = new Y.Doc();
    const persistence = new IndexeddbPersistence(room, doc);
    persistence.once('synced', () => {
        console.log(exactTime() + ' local content loaded');
    });
    const wsProvider = new WebsocketProvider(websocket, 'prsm' + room, doc);
    wsProvider.on('sync', () => {
        console.log(exactTime() + ' remote content loaded');
    });
    yNodesMap = doc.getMap('nodes');
    yEdgesMap = doc.getMap('edges');

Example output:

09:49:47:513  remote content loaded
09:49:47:516  local content loaded

I believe y-websocket implemented with a bug which did not wait both side exchange the initial vector, then sent out the initial empty data to client, then client thought it is "synced" but indeed the server side did not load the yjs doc from leveldb yet.