In an application execution system having a plurality of application servers, each application server stores a plurality of applications, and has computational resources for executing applications in response to received requests. Each application server also includes instructions for loading a respective application into volatile storage and executing the application in response to a request from a client, and for returning a result. A generic application instance may be cloned, creating a pool of generic application instance clones that can be loaded with code for a requested application to produce an application instance. The application instance can then be stored in a cache to be used for a future application request.