The latest build fixes the issue with the cache delete.
The biggest gains you get with the cache is when multiple users access the same reports. If you have a report that contains the user login, the cache individual for each user (the login most likely changes the report output). You may want to consider if the use of the individual cache is beneficial.
The use of the cache is designed to be invisible to the user (user does not have to worry about the cache). One can skip the cache usage though by adding &cache=0 to the URL. We could make it optional so that using this would delete the cache item (the item will expire automatically after the defined period).