Copter loses altitude when changing directions

I have a X350 Pro and when it’s running on a mission and changes directions there is a small loss in altitude (5 to 10 Meters). The altitude does recover but the problem is I also have a 3D gimbal which is a little overweight for the 350 Pro and when the copter starts to lose altitude the machine has a really tough time recovering from the downward momentum with the Gimbal and camera attached. 5 to 10 meter can quickly turn into a 20 meters.
Is there a setting that will allow the copter to maintain a more absolute altitude?

Please provide tlogs and/or dataflash logs to help answer your question concerning your issue.

Honestly, it just sounds under powered, use a 4S battery might help, or a smaller capacity battery that is lighter.