A data processing apparatus and method which handle data processing requests is disclosed. The data processing apparatus comprises: reception logic operable to receive, for subsequent issue, a request to perform a processing activity; response logic operable to receive an indication of whether the data processing apparatus is currently able, if the request was issued, perform the processing activity in response to that issued request; and optimisation logic operable, in the event that the response logic indicates that the data processing apparatus would be currently unable to perform the processing activities in response to the issued request, to alter pending requests received by the reception logic to improve the performance of the data processing apparatus. Accordingly, the time available whilst waiting for unit to become available can be utilised to analyse the pending requests and to optimize or alter these requests in some way in order to subsequently improve the performance of the data processing apparatus. Hence, once the component is then able to deal with the altered requests, the altered requests will then enable the data processing apparatus to operate more efficiently than had the original requests been used.