Yes, that's if the software is optimized well for any environment is what I'm saying. "FreeFlarum" doesn't seem optimized enough to run on VPS or shared.
Let me put it this way; The original reason why vB4 got shafted early, and beyond is because of the codebase. Even if you host vB4 with no plugins, the server drags its feet, because Internet Brands didn't know how to code vB without making the software bloated. The more bloat you have, the more queries the server receives from the software itself, and then send it back to server.
That is WITHOUT any plugins. I would imagine with plugins - that overhead? Forget hosting it on shared or VPS.
This is not just me regurgitating what others said, this has been my experience, too. I ran a small vB3 website that had vBSEO, then, went big by buying a few Modern Warfare websites. One was vB4, one was xenForo, the winner was xenForo. Both didn't have plugins.
I even posted videos...
Once I transferred CoDForums from old server to new server, errors ensued. In
THIS case, vBSEO was running in the background. The server was doing more work than necessary - its because vBSEO wasn't well optimized. Anyway, I then transferred vB3 to vB4, it killed my site. From here, vB4 was migrated to xenForo. The rest, they say - is history.
In 2018, I am reminded of how stupid vB4 was when I purchased a PlayStation 4 Forum, and transferred vB4 to xenForo 2. Jesus. Psh.
Garbage.