Performance optimizations for emulators

One embodiment illustrated herein includes a method that may be practiced in a computing environment with a guest architecture running a native architecture system. The method includes acts for handling function calls. The method includes receiving a call to a target binary, wherein the call is in a format for the guest architecture. The method further includes determining that the call is to a binary that is a hybrid binary. The hybrid binary includes a native function compiled into a native architecture binary code using guest architecture source code and a specialized thunk to handle an incompatibility between the guest architecture and the native architecture. The method further includes invoking the specialized thunk to allow the native function in the hybrid binary to be executed natively on the native architecture system.