Just in Time (JIT) compilers and their aggressive speculative optimizations reduced the performance gap between dynamic and static languages drastically. To successfully speculate, compilers rely on the fact that the observed variability of programs at run time is low. However, there remain patterns of variability, which are hard to capture with heuristics. Specifically, ephemeral, warmup, rare, and highly indirect variability are challenges for today’s compiler heuristics. As a consequence, they can lead to reduced application performance. However, these types of variability are identifiable at the application level and could be mitigated with information provided by developers. As a solution, we propose a metaobject protocol for dynamic compilation systems to enable application developers to provide such information at run time. As a proof of concept, we demonstrate performance improvements for a few scenarios in a dynamic language built on top of the Truffle and Graal system.