As systems grow more and more complex, raising severe evolution and management difficulties, computationnal reflection and aspect-orientation have proven to enforce separation of concerns principles and thus to address those issues. However, most of the existing solutions rely either on a static source code manipulation or on the introduction of extra-code (and overhead) to support dynamic adaptation. Whereas those approaches represent the extreme of a spectre, developpers are left with this rigid tradeoff between performance and dynamism. A first step toward a solution was the introduction of specialized virtual machines to support dynamic aspects into the core of the execution engine. However, using such dedicated runtimes limits applications' portability and interoperability.In order to reconcile dynamism and performance without introducing portability and interoperability issues, we propose a dynamic reflexive runtime that uses reflection and dynamic compilation to allow application-specific dynamic weaving strategics, whithout introducing extra-overhead compared to static monolithic weavers.