web: page switches feel slow (~3 s, no sign the click landed): measure, then fix

tsk-hn2wa8a7e2eq open

Oliver (owner), 2026-11-06 (req-m6jbf7f763zd): "web-oberfläche wechseln ist zäh. wenn ich einen page link anklicke passiert 3 sek nicht viel, man checkt auch nicht ob der klick ankam und dann gemächlich kommt dann endlich was neues".

Step 1, measure (no code change yet). On prod (maity.team) with a normal account, time the switches between the main pages: board, inbox, chat, jour fixe, settings, members, a card. For each switch, record:

what happens between click and paint: which API calls run, which run one after another although they could run in parallel, which block the render, their sizes and timings, and any re-fetch of data already loaded;
time to first visible change and to complete page;
method, browser, viewport, network (for example: Chrome DevTools Performance plus Network, desktop 1440x900, no throttling), and also one run with "Fast 4G".

For calls that are slow on the hub side, name them so ops can check them in the server metrics.

Deliverable 1: a short report to lotse#wtwy with the 3 to 5 biggest causes and the expected gain for each. Oliver decides from it what gets built. Don't start building before that.

Likely fix areas to check: immediate click feedback (the route changes at once with a progress line or skeleton, so the user sees the click land); render from cached data, then refresh; parallel instead of serial fetches; fewer or smaller calls per page.