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As part of the 6.0 release of WordPress, the new performance team has been hard at work to improve the performance of term queries. There are many term queries on the average page load and improving these improves the performance of WordPress in general.
Improvement to term query caching.
Queries run by WP_Term_Query have been cached since 4.6. The way these caches are primed and handled has been improved in WordPress 6.0.