Abstract: According to aspects of the invention there are provided methods and apparatus for monitoring, analysing and/or optimising the performance of a mobile device. The mobile device includes a memory with computer readable instructions stored thereon associated with a diagnostic application, which when executed on a processor, has a first level of permissions for accessing the mobile device, and associated with a performance monitoring component, which when executed on the processor, has a second level of permissions for accessing the mobile device. The diagnostic application and performance monitoring component communicate to retrieve performance-related data associated with execution of an application on the mobile device, where the performance-related data is accessible using the second level of permissions.