This Issue can be resolved in few steps:
CMD to Check Cache usage:
free -g
You can use different flag as per your requirement this will provide you the memory details.
where u can see the memory associated with Cache.
If 50% of the total memory seems to be allocated to Cache,It can be cleared.
And trust me it provide a great help in reducing the system CPU IO.
echo 1 > /proc/sys/vm/drop_caches
This can be used in Production Environment in business hours without any harm and prior notification.