Code Caching 

DCE generates PHP code and XML for new content elements during TYPO3's bootstrapping. To decrease database queries during this process, DCE 2.2 introduced an own small CacheManager.

The code cache for DCEs is always enabled.

This cache contains generated DCE registration, TCA and FlexForm code. It is independent of the per-DCE "Cache DCE frontend plugin" option, which controls whether the frontend controller action is cacheable.

Why DCE ships its own Cache Manager? 

In DCE 2.1 the TYPO3's core cache manager has been used to cache DCE code. But TYPO3 does not allow to use its Cache Manager during bootstrapping (limbo mode) in TYPO3 10 anymore. Therefore DCE provides it's own cache manager.

The shipped cache manager stores generated files below var/cache/code/dce.

When clearing TYPO3's system caches in the backend or with the cache:flush CLI command, the DCE code cache is rebuilt automatically.

When warming an empty cache from the command line, run cache:flush --group system before cache:warmup --group system so the DCE code cache exists before TYPO3 builds its system caches.