[Stargate38]

I noticed that JD2 was taking a long time to load the menu bar (and other GUI elements), so I opened Resource Monitor while it was stuck and it showed that JD2 was reading EVERY SINGLE FONT from A-Z in my C:\Windows\Fonts directory, even fonts it NEVER uses! And I have thousands of fonts that I use for all the programs I run on my PC (WordPad, LibreOffice, etc.). WHY is it doing that? It should only read the fonts it needs to display the GUI elements, not all of them. Please fix that, because it wastes unnecessary time to read fonts it doesn't even use, and I could have downloaded quite a few files in that time.

11.11.17 20.06.52 <--> 11.11.17 20.21.46 jdlog://4146914015941/

[Jiaz]

That happens deep inside Java itself. Out of our reach. Java has to scan the fonts folder to build its Fontname to Filename map.
How many fonts do you have on your system installed because this process should NOT take long. In fact on my windows systems the startup time is less than 5 secs.
How long does a cold start take for you? cold start = after windows reboot
From your Log I can tell that your JDownloader installation is very old because it still is installed in ProgramFiles folder but since long time the installer installs to AppData.