It will only significantly reduce the load-time if you have really not enough RAM - you should have a look on the taskmanager and you could use tools like the governance dashboard:
As Marcus suggested, this may have an impact if you are runnng at 100%. Often, better run time savings can be made by making the application optimized.
If you are unfamiliar with optimization techniques, have a look at this blog for assistance:
Maybe you haven't only one bottleneck, for example loads which aren't multi-threaded. Also important are configurations from OS and BIOS - I think you will find here http://community.qlik.com/docs/DOC-5356 some hints.
