A programmable vehicle or engine diagnostic tool includes an interface for receiving a signal relating to a performance parameter of the vehicle or engine, a user interface, and a central processing unit, for processing the signal to generate information for presentation to the user. The system utilizes a fast access non-volatile random access type main memory to store the programming for execution by the central processing unit. Techniques are disclosed for moving applications to the main memory, for fast boot at subsequent operation, based for example on program usage or user selection.