Ten percent doesn't sound very big.
Sometimes as a tester we can only make so much of a dent. Can we test the product and coach our team towards quality so that the app responds 10% faster? Can we improve the quality enough to get 10% less bugs, crashes, support requests? 10% less clicking or tapping to accomplish a task.
As a project manager, we only have so much effect on the outcomes. Sometimes you get what you get, the team was decided and the contract finalized before you got the project. Can we get through the backlog 10% faster? Can we cut the noise by 10%? Can we have 10% fewer meetings? Can we meet budget within tolerances? Can we make a big enough dent in the process that we make meaningful gains in milestones and delivery?
It doesn't sound like much but 10% can be the difference between getting repeat business, 10% can be the difference between making the deadline or not.
You might look for deeper wins but having the outlook that anything can be improved by at least ten percent might just be enough to make or break the project.