We really need to know what is using all the cpu, so run top in terminal and then type an upper case "P" to sort processes by processor usage %age.
This from man top shows what other sorting you can use.
SORTING of task window
For compatibility, this top supports most of the former top sort keys. Since this is primarily a
service to former top users, these commands do not appear on any help screen.
command sorted field supported
A start time (non-display) No
M %MEM Yes
N PID Yes
P %CPU Yes
T TIME+ Yes