A computer implemented method optimizes memory page sizes during runtime. A process is identified from a policy file. The policy file contains at least one policy based threshold. A resource usage profiler monitors the process during runtime. The resource usage profiler determines whether the process exceeds the set of stated desired policies from the at least one policy based threshold. If the process exceeds the set of stated desired policies from the set of policy based thresholds, a performance projection for the process is executed to determine whether the process would experience a performance benefit from a different page size. Responsive to determining that the process would experience the performance benefit from the different page size, the page size for the process is changed.