Looking at our performance metrics as part of our chores, I noticed that about 7 days ago the rendering times for the homepage went up and stayed high: https://grafana.wikimedia.org/d/vGq7hbnMz/special-homepage-and-suggested-edits?orgId=1&from=1718582400000&to=now
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**Acceptance Criteria**:
* [ ] figure out why homepage performance got much worse on June 18th / 19th.
**Note**:
This seems to happen between the Group 0 and Group 1 deploy, so somehow I doubt that it is related to the train per se. But maybe some caching config change or something?
**Excimer profiles:**
* https://performance.wikimedia.org/excimer/profile/eb90399943053e8e
* https://performance.wikimedia.org/excimer/profile/5e8ffc81453b827c
* https://performance.wikimedia.org/excimer/profile/3e23471a31656a7e
* https://performance.wikimedia.org/excimer/profile/6fd3d55e2417e190
* https://performance.wikimedia.org/excimer/profile/11694b1482dc0380
**XHGui profiles:**
* https://performance.wikimedia.org/xhgui/run/view?id=667bce24be639ea503044362 (fast)
* https://performance.wikimedia.org/xhgui/run/view?id=667bce5bb6b0c73de92d3530 (fast, after hard refresh)
* https://performance.wikimedia.org/xhgui/run/view?id=667bcdd5534105702ed0e2e9 (slow, after hard refresh, different person)
* https://performance.wikimedia.org/xhgui/run/view?id=667d521c1e076ad57073b11e (slow, after changing topics, cache-miss in main thread)
* https://performance.wikimedia.org/xhgui/run/view?id=667d51e229fe83b0bc29881b (fast, almost all of the wall-time is spent in deferred updates)