Code hotspot encapsulation

A method is disclosed of encapsulating code hotspots and corresponding data from a large scale computer application and isolating the hotspots into standalone micro-routines. The hotspots are identified S102, S104 and selected S106 for encapsulation S108. Encapsulation involves extracting hotspots and their data dependencies, into standalone micro-routines that can be modified, compiled and run independently from the original application. The data dependencies are captured by applying a plurality of different data sets to the same hotspot. Optimising strategies may be applied S110 to the micro routines in isolation and the results tested S112, S114 without having to re-execute the entire application. The method can be applied at source code level S108_I, compile and link level S108_II or executable level S108_III. Hook functions may be used to perform the extraction of the hotspots.