Allow to stop a preload in process

[alfonso100]

Is your feature request related to a problem? Please describe. It'd be good if we can allow to stop the preload process. It was an old request from customers and we just got a new question about this.

Describe the solution you'd like Add a button to stop an ongoing preload, without clearing the cache. Just pausing the process and allowing to resume it.

Additional context https://secure.helpscout.net/conversation/2006483621/367843?folderId=273766