Do profiling of the sitemap

The sitemap xml takes a looong time to load. We should at least get to an understanding of where that time is spent.

Can we query more efficiently?

Is the XML rendering slow?

Can we grab the data from the indexer component instead? -> I'm pretty sure we have the necessary data already here in memory, so if the querying is the bottleneck then this would make a big difference.

It's also worth looking at the cloudflare settings, I have the impression this isn't being cached, even though it should be very cacheable.

Begin by profiling the sitemap XML request end to end, separating query time, XML rendering time, indexer data access, and Cloudflare caching behavior. Done means the main source of the delay is identified and the findings are recorded, including whether querying the in-memory indexer data or adjusting caching should be pursued.

Written by the indexing model from the issue text.