I realize that vb 3.8 is DEAD, and apparently no one will respond to these questions any longer.

But if your config.php file is set like this (no caching), then is "Rebuild Post Cache" actually useful for fixing certain issues?
(It takes forever to run when you have a large number of posts...)

// Here you can configure different methods for caching datastore items.
// vB_Datastore_Filecache - to use includes/datastore/datastore_cache.php
// vB_Datastore_APCu - to use APCu (which replaces APC)
// vB_Datastore_XCache - to use XCache (not available for PHP 7+)
// vB_Datastore_Memcached - to use a Memcache server, more configuration below
// $config['Datastore']['class'] = 'vB_Datastore_Filecache';
I know that in the database there is a datastore table which contains different "small" cache things like forumscache, stylecache etc, but I see no posts cache or threadscache tables in there.