Since TURN simply relays streams as they are, a TURN server will not help with a user's CPU limitations.
So a user with insufficient CPU would be the only peer to display poor performance. The remaining peers would not be impacted other than potentially low quality and/ or intermittent hangs and empty frames being displayed by the peer that is over capacity.
To reduce the load of the individual peers, you may wish to consider using our MCU/SFU instead.
Other articles you may be interested in: What is TURN?| Where are Temays TURN servers located?| How can I check if TURN connectivity is enabled?| How can I enable TURN for my App?