@leocg I understand that this might be a struggle for you and that you cant control a whole forum of people shouting at you but i don't think you understand.
The person you have recently replied to was using the same download. This rules out it being the website which means its Opera. I have been having this problem a lot and for a while. It used to be perfectly fine until one day my downloads started to drop and haven't gone back up since. I am now running at 10 - 50 kbps, 100 if I'm lucky, whereas I used to run at 1500 - 2000 kbps. I very much doubt this is anything but operas side of things but I could be wrong.