[wp-trac] [WordPress Trac] #59583: Patterns: `theme` attribute not inserted in Template Part blocks

[WordPress Trac]

#59583: Patterns: `theme` attribute not inserted in Template Part blocks
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 Reporter:  Bernhard Reiter           |       Owner:  Bernhard Reiter
     Type:  defect (bug)              |      Status:  reopened
 Priority:  high                      |   Milestone:  6.4
Component:  General                   |     Version:
 Severity:  major                     |  Resolution:
 Keywords:  has-patch has-unit-tests  |     Focuses:  performance
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Comment (by flixos90):

 @bernhard-reiter @gziolo I have spent some time researching this further
 in terms of performance impact. Here is my summary / conclusion:

 * [56805] seemed to have a massive performance impact (in my benchmarks,
 `wp-total` improved from ~105ms to ~85ms for TT4).
 * However it introduced a functional bug, which [56818] then addressed,
 while however also reverting almost all the performance benefit.
 * The solution implemented in
 https://github.com/WordPress/gutenberg/pull/55217 and
 https://github.com/WordPress/wordpress-develop/pull/5455 improves
 performance again slightly, however ''far'' from how [56805] initially
 seemed to do (`wp-total` 102.5ms vs 103.8ms in my current benchmark with
 TT4)
 * Unfortunately, the apparent performance enhancement [56805] came almost
 entirely from the bug it introduced. Due to no longer injecting the
 `theme` attribute to all `core/template-part` blocks, those blocks would
 no run any of the logic within
 https://github.com/WordPress/gutenberg/pull/55217/files#diff-
 28f36bb64fbbc8ce728db401b1e4cf30c9f44db7f5dcce1b7b0cc9ce60b1a209L22, which
 has a considerable cost.
 * This led us to believe there was a major performance improvement behind
 the change, but unfortunately most of it came from the bug.
 * I think it is worth completing the work on
 https://github.com/WordPress/gutenberg/pull/55217 and
 https://github.com/WordPress/wordpress-develop/pull/5455, since they bring
 a decent performance improvement. However, the greater part of the
 associated cost comes from retrieving the file contents from block
 template part files (and block template files), for which I have
 identified a separate solution in a new ticket #59600. The PR on that
 ticket leads to performance improvements between 5-10% for all block
 themes I've tested it with so far.

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Ticket URL: <https://core.trac.wordpress.org/ticket/59583#comment:20>
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