This experience report describes a semi-Agile journey of a test expert on a air travel information system development project. The organization set-up is not 100% Agile, with in-house components being developed by Agile teams while third-party components are developed and deployed by vendors using more traditional methods and pre-planned delivery packages. Besides the challenges of the project's setup, the lack of clear non-functional requirements posed significant extra obstacles for testing. In this article, I retell how I navigated through ambiguous performance requirements, collaborated across multiple team settings, and implemented a stepwise approach to performance testing that led to significant code refactoring and improved system performance. Further insights discuss the use of novel technologies - such as Large Language Model applications - to elicit non-functional requirements from stakeholders.