Related to T228553: Add category count to Special:Statistics, it would be nice if https://www.mediawiki.org/wiki/Special:Statistics included counts for the number of pages per namespace. A user could then see how many templates, how many user pages, etc. a wiki has.
See also: T385002: Special:NamespaceInfo should include counts of {{PAGESINNAMESPACE}}
We should have a database table storing the count. $wgAllowSlowParserFunctions can then be removed.
(Is database indexes sufficient?)
I think Special:NameSpaceInfo is a better location for these data, rather than Special:Statistics. Hence, T385002: Special:NamespaceInfo should include counts of {{PAGESINNAMESPACE}}.
There's probably little reason to include these data in both of them.
And Special:NameSpaceInfo is relatively new, so wasn't available when this task was originally filed in 2019.