By default the application allocates only 5GBs of memory for itself. In order to allow it to take advantage of the available resources you can assign more memory using the Memory Settings option which is available under the Application Settings page. Important note: please do not allocate all the available memory to the software. The operating system and other applications running in the background also require resources. The ideal amount is around ⅔ of the available memory  if you intend to run Twin or Explore analyses only. Examples: allocate 5GB out 8GB, or 12GB out of 16GBs, 24GB out of 32GB.