Kindle fire tablet is the pro versions of kindle e-reader device because of too much accessibility with many new features and function along with high performance but still many users complaint about the fire tablet running slow. The reason behind the issue mainly because of user side less free storage means memory issue so delete unwanted files, transfer data and download anything is quite risky so always use antivirus and etc. for slow performance. Apart from this you can restart your device and reset it with default factory reset option for this you can check the steps on the website.