If your device was running slow and is too hot. Those are the signs of a device's CPU working its a** off, this can then later be noted with the fact as you mentioned that it needs to be charged every one hour.

There is a very simple solution: backup necessary data and reflash. To reflash follow the guide here..

The longer alternative solution highly depends on your skills with linux (especially in CLI realm). In most cases the reason why the CPU is working its a** off is because there's at least one offending process (programs/applications/or however you may want to call it) that is taking forever to load. My advise is to use tools like top (htop if you have it installed), the first name that appears on the list below the words `COMMAND' indicates the offending process (which can be verified with checking under the %CPU column for that command). I would then kill it by quitting top and type in pkill "insert name of offending process without quotes".