This script changes download speed limit depending on the item being currently downloaded. More specifically - depending on the category this item belongs to.
How to use: save the script into ScriptDir and select it in option "Extensions". The script adds two setting sections - "SpeedLimit - Options" and "SpeedLimit - Categories", check the first section and (more important) add speed limits in the second section.
The script changes the speed only when current category is changed. That means you still can change the speed limit manually and it will be kept until a download item with another category becomes active.