Is there an overhead if we keep trace enabled always for every calls made during Testing.
@kamnaOne Trace session can support 10 request/response transactions per message processor through the selected API proxy. In Edge cloud, with 2 messages processors handling traffic, 20 request/response transactions are supported. A trace session automatically stops after 10 minutes if you don't manually stop it. I would imagine a minor performance hit if you enable trace, as message processors have to do an extra task. So i wouldn't recommend you enabling trace for every API call. Also it's unnecessary.. use trace if you notice issue and want to debug.
Yes . Its always better to enable trace when you see any issues & want to debug.