Preparing the track reconstruction in ATLAS for a high multiplicity future

The track reconstruction algorithms of the ATLAS experiment have demonstrated excellent performance in all of the data delivered so far by the LHC. The expected large increase in the number of interactions per bunch crossing introduces new challenges both in the computational aspects and physics performance of the algorithms. With the aim of taking advantage of modern CPU design and optimizing memory and CPU usage in the reconstruction algorithms a number of projects are being pursued. These include rationalization of the event data model, vectorization of the core components of the algorithms, and removing algorithm bottlenecks by using modern code analysis tools. Recent results of the advances made in these ongoing projects indicate up to three-fold speedup in the optimized modules while in some modules the code size could be reduced by up to 97% leading to higher readability, maintainability and decreased interface complexity.