Compare performance of WordPress 4.4 through 4.7

[bobbingwide]

One year on from producing the unpublished results for WordPress 4.4 and each of the top 12 plugins I want to produce a new set, to see if the plugins are more or less efficient than their previous versions.

• I needed to create a new 'vanilla' control for WP 4.4 and the base set of 35 plugins.
• To ensure comparable results I needed to eliminate from the input file those queries that caused more than one transaction to be run in the server.

The results indicate that WordPress itself has slowed down.

• It would be nice to know the main causes of this performance degradation

• and whether or not anything can be done about it.

• Prime candidates are the REST API, and action and filter hook logic changes in 4.7

[bobbingwide]

See vanilla-44-47-summary.ods for the result set that indicates that the run time server performance has increased by 9% average.

WordPress 4.7 is slower than WordPress 4.4 due to:

1. Unverified performance degradation in WordPress 4.5 ( added 0.5% )
2. Additional logic and query for 'can_compress_scripts' ( added 1.55%, in WordPress 4.6 )
3. Additional logic and query for Custom CSS ( added 2% )
4. Addition of REST API
5. Increased number of hook invocations
6. New hook logic - difficult to measure
7. Other changes