Soap Ui Open Source - Terribly slow to open

Good morning all

I'm using Soap UI Open Source since months and since then the opening of the interface is terribly slow, I means it can take 10 minutes.

I can see the executable in my task manager. Sometimes after minutes, I kill the process, start Soap UI again and, often, I get then the interface faster (less than one minute).

I'm behind a corporate firewall; perhaps should I disable something to make it faster?

(sorry if my post is in double, I've already searched for a solution, never find one).

Thanks!

(I'm using the very latest version 5.6.0; reinstalled this morning)

Christophe