Preload is an “adaptive readahead daemon” that runs in the background of your system, and observes what programs you use most often, caching them in order to speed up application load time. By using Preload, you can put unused RAM to good work, and improve the overall performance of your desktop system.
Most Linux users should install Preload using their distribution’s Software Center or repository, and simply installing the program will be all that is needed. But this article explains much more about Preload, including various configuration options:
Preload is also featured in this video: