Linear voltage regulators produce alot of heat , to cool it down you can add heatsink on both side of pcb.

Also what greatly supports it: A slight airflow over it with a case fan is always welcome. This usually is good enough to keep temperatures in an acceptable range.

As @ciornyi mentioned, linear regulators produce a lot heat depending their load. This is due to their working principle: The differential voltage between input and output is transformed into heat via the current flowing through them. So the larger the current pulled, the higher the heat output. (Also true the larger the differential voltage between input and output).