A system and method for dynamic preloading of classes through memory space cloning of a master runtime system process is presented. A master runtime system process is executed. A representation of at least one class is obtained from a source definition provided as object-oriented program code. The representation is interpreted and instantiated as a class definition in a memory space of the master runtime system process. The memory space is cloned as a child runtime system process responsive to a process request and the child runtime system process is executed, inheriting the memory state of the parent, which reflects the data structures and state corresponding to the preloaded classes.