We have a default event for all the ambient emitters in our game. It has a gain effect on the master track, with automation, making it easy for us to set it from Unity, if we want some instances to be quieter. Should we worry about performance cost of having a gain effect on all our emitters, or does a simple “effect” like that not cost anything worth thinking about?
In terms of performance, using a gain effect has a negligible impact. In fact, you could put a gain effect on every track of every event in your project and still barely notice any performance overhead.
That said, if you do run into any issues with performance, you could connect to your project via Live Update and use the Profiler to record gameplay and identify whether/where there are any issues.