Cache 

The extension registers a cache named handlebars that stores compiled Handlebars templates. The cache is registered automatically on extension activation; no manual setup is required.

The default backend is the TYPO3 database cache. To use a different backend, add an override to your extension's ext_localconf.php file:

if (!isset($GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['handlebars']['backend'])) {
    $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['handlebars']['backend']
        = \TYPO3\CMS\Core\Cache\Backend\SimpleFileBackend::class;
}