If you spend a few minutes setting up JDownloader properly, you'll be able to speed up this download manager. The following guide will give you all the keys for faster downloading with JDownloader.
This beginner's guide to install JDownloader will help you to get this download manager properly set on your computer.
If you want to download files with JDownloader, take a look at this tutorial.
If you need help when using JDownloader, this user's manual will guide you step by step.