1. A method for recording core data of a computer process, wherein the computer process provides trace data, the method comprising: responsive to an entry of first trace data in a trace file resulting from processing of a first trace point by a core data processing program, storing a first set of core data comprising an image of a memory for the computer process, as base core data; splitting the core data processing program into two threads, wherein the image of the memory is monitored for a change in the image of the memory by a first thread; responsive to detecting the change in the image of the memory, recording the change in the image of the memory by the first thread of the core data processing program as first pending delta core data comprising a record of each address and corresponding data contents in the image of the memory that has been modified since the base core data was stored; monitoring for production of further trace data by a second thread; and responsive to production of the further trace data produced for the computer process for a second trace point as an entry of second trace data in the trace file, storing the first pending delta core data as a first set of delta core data, wherein the first set of delta core data comprises a record of any change in a current image of the memory for the computer process with respect to the base core data, and wherein the first set of delta core data represents a difference between contents of the image of the memory at the first trace point and the contents of the image of the memory at the second trace point, and wherein the delta core data is recorded incrementally, each time the change is made in the image of the memory, and wherein the change in the image of the memory is logged as pending delta core data until new trace data is produced at which point the pending delta core data is saved in association with the new trace data as a new set of delta core data.