Need advice to improve current RDS

Currently I am running a m3.medium SQL Server RDS(20GB storage without IOPS). CPU utilization is under 50% for most of the time(~90%). However, during peak hours(~10%) CPU utilization will hit 100% and my website become extremely slow.

DB instance details

Instance Type   : db.m3.medium
vCPU    : 1
ECU : 3
Memory (GiB)    : 3.75
PIOPS-Optimized : -
Network Performance : Moderate

Attached with the overall metrics of my RDS 

i.stack.imgur.com/nZTIB.jpg

How can i reduce the chances of my RDS hitting 100% CPU utilization? Does enable IOPS will helps? Or should i upgrade it into a better instance?