Codec transcoding takes a lot of CPU cycles.

Solution

Make sure ALL devices (OP and TP) have these settings set to Yes:

Note that only OP devices will have only first option available and only TP devices only second option available. Mark them YES anyway.

Detailed problem description

Example in which you can see that 284 calls takes 287.9% of CPU for Freeswitch:

In the Call List page you can observe which calls are transcoded. They are marked by RED icon:

Go through all your devices (OP and TP) and set these options:

These options will force Freeswitch to use same codecs for both legs 99% of the time. Detailed description here: M2 Codec Negotiation

Also make sure your devices have same codecs available.

This is just an example how it could look like. On your system you can have different codecs enabled: