Described is a system and method that separates a managed code runtime library or program into four parts, comprising a header, resources, metadata and method implementations. The metadata and some or all of the resources are maintained in system memory (RAM) the entire time that the program is running. The method implementations and any non-maintained resources are loaded on demand, and then discarded such as via garbage collection. The amount of memory consumed by a managed code program is thus reduced relative to non-separated environments, but because the metadata and selected resources are in memory, the program execution is highly efficient due to significantly reduced access of data in non-volatile storage. The parts of the assembly that are maintained in RAM can be saved as code library files, providing shared use by programs and efficient loading by eliminating any need to again parse a program to identify the separate parts.