Cutscence ish thing happenining

The cache is pre-downloaded images/other files used in the game. If you delete it and load up the game, the game starts downloading it again, and you might see that images for prayers/spells/buttons in the menus, items in your bank, etc. take a little longer to load because they have to be downloaded again where the game would normally pull them from the cache.

The game updates the cache after updates, and files were getting corrupted and causing problems for some players, so clearing the cache was definitely a good solution some of the time. I know it worked for me when I would get the "already logged in" error.

I think they may have done something to fix the underlying issue though, because over the last few weeks the game has been downloading cache files every time I log in, and haven't had any kind of issues in that time either.