[wp-trac] [WordPress Trac] #59544: Performance: Skip iteration in block supports elements when not necessary.

[WordPress Trac]

#59544: Performance: Skip iteration in block supports elements when not necessary.
-------------------------+-----------------------------
 Reporter:  dmsnell      |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  normal       |  Milestone:  Awaiting Review
Component:  Editor       |    Version:  trunk
 Severity:  normal       |   Keywords:  has-patch
  Focuses:  performance  |
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 **Quick notes**

  - This is intended to address performance regressions in the 6.4 beta
 release in combination with the front page of `twentytwentyfour`. It's
 half a bug-fix and half an enhancement.
  - It needs a backport into Gutenberg because it comes over in a Gutenberg
 package. I am going to ensure this happens as it needs to, but given the
 relation to the release, I would prefer we fast-track this into Core first
 if it finds favorable review and confirmed impact.

 **Description**

 Previously there have been three ways in which the block supports elements
 code has been performing computation it doesn't need to.

  - It checks for every possible style attribute on a block even if there
 are no possible style attributes available on the block.

  - Once it determines that it needs to add a special class to a block it
 continues scanning through the rest of the attributes.

  - It constructs dot-separated literal key paths for the attributes and
 immediately and repeatedly calls `explode()` on them to create an array at
 runtime.

 The combination of these three factors leads to an outsized impact of this
 function on the runtime and memory pressure for what it's doing. This
 patch removes all three of these inefficiencies:

  - If no elements style attributes exist on the block it immediately
 returns and skips all further processing.

  - It stops scanning block attributes once a single one is found that
 imposes the requirement for the extra class name.

  - It constructs array literals for the key path instead of strings. This
 removes the need to artificially join and explode the keys at runtime.

 There should be no functional or visual changes in this patch, but it
 should reduce the overall runtime of page renders and require less memory
 while rendering. The impact will be proportional to the number of blocks
 rendered on a page.

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Ticket URL: <https://core.trac.wordpress.org/ticket/59544>
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