The story is I have to use this little coffee machine-PC because my heads gave it to me, so I can't add more RAM nor modify anything. That's why I installed Peppermint on a Pendrive, so to have a smooth experience and to overcome this limit...

However I assure you that even with 1Gb it works fine. I use to open some Libreoffice sessions, Chromium with 3 or 4 tabs, and another program called Xyphos, and it never thinks too much about what to do

however thank you for the advices!