Noticeable screen lag when unplugged

/e/ version: lineage_FP3-userdebug 9 PQ3A.190801.002 eng.root.20200428.185457 dev-keys
Device model: FP3
When it started to occur: 03/05/2020, After flashing
Reproducible with the last /e/ version: yes
Reproducible with LineageOS: N/A

Summary

When device is plugged in, the UI feels smooth when navigating. When unplugging device UI feels laggy.

Steps to reproduce

Flash device, setup and unplug device.

What is the current behavior?

There is a noticeable change in UI framerate. (Not sure how to actually monitor this)

What is the expected correct behavior?

UI framerate should be the same.

Relevant logs (adb logcat)

N/A

Relevant screenshots

Workaround

Possible fixes