Search in Browse Public Rooms fails or returns non-matching results on large directories

[mremond]

Description

The "Browse Public Rooms" feature appears to struggle when browsing a large public room directory (e.g. a conference service with ~16,000 rooms). The room browser feels overloaded at this scale.

Search within the directory does not work reliably: entering a search term sometimes produces no results, and other times returns results that do not match the entered term.

Steps / Context

1. Open "Browse Public Rooms" on a large public directory (~16k rooms).
2. Enter a search term.
3. Observe that either nothing happens or the returned results do not match the search term.

Early search attempts reportedly worked, but after trying several different search terms the search began to behave inconsistently, suggesting the results degrade over repeated queries.

Note: The search happen locally from the room already downloaded. I do not think there is a spec for room search on the server.

Expected behaviour

Entering a search term should reliably return rooms matching that term, even on large directories.

Actual behaviour

Search either returns no results or returns results that do not match the entered term, and reliability degrades after multiple queries.