The reason I have so many links in the downloads tab (most of them are completed/finished ones) is to guard against duplicates. If I clear the downloads tab of finished links, then in case I accidentally load something I have already downloaded, JD2 warns me of the same, and saves me the times and the bandwidth of redownloading it. Hence, I haven't cleared the downloads tab in over 3 years.
Most of them are imagetwist/imx.to/vipr.im/k2s/filefactory, etc links.
I suppose I will have to forego dupes-check in order to save on memory, and clear the finished links.
Thanks for the info.
Anyways, here is the screenshot of the About JDownloader.
https://imgur.com/gnvBmSx