Cache file sizes of core block style files.

[spacedmonkey]

Introduced in #58528 / [56044], there is now cache for file lookups for core block styles. This was to save file lookups and improve server response time. However, when styles are processed in wp_maybe_inline_styles a file lookup is done using wp_filesize to get the file size and if the file exists. These lookup can be expensive. As there is already an existing transient cache, reuse that to also cache the file size of the files.

Trac ticket: https://core.trac.wordpress.org/ticket/59596

Trac ticket: https://core.trac.wordpress.org/ticket/59596

[joemcgill]

Thanks @spacedmonkey. Conceptually, this idea makes sense. It would be great if someone could do an initial analysis of the current performance cost of these wp_filesize lookups prior to us getting into the implementation details, in order to help prioritize this work appropriately.

[spacedmonkey]

I think this ticket has a lot of benefits. Recalulating file size for files that do not changes is wasteful. Some level of change the is cleared on WordPress core update makes sense to me.

Love feedback from @flixos90 and @mukesh27.