@rysiek @stitchxd @barkin @sda @kris

Well I have used:

GNUSocial
Friendica
Diaspora
Mastodon

On my own servers and I can tell you right now that where those 4 pieces of software are concerned, GS is the lightest. Where Mastodon is the heaviest. (Resource wise, RAM, CPU, & DISK usage.)

So my statement is based on experience.