I should point out real fast that HRU affects -all- websites, although some scripts are more prone to it than others.
And a quick explanation of HRU is also waranted for zenon since no one's explained it at all in this thread.
In short, High Resource Usage is a server-security system that prevents 1 account from crippling the server by hogging all of the available CPU or RAM for extended periods of time (30 seconds). Most scripts will tend to spike the CPU on load to say, 30%, but they do so for less than a tenth of a second. I'm quoting experience here, I've actually watched the server do that. These do -not- cause High Resource Usage because it's not extended.
What can cause it however is automatic updates, batch uploading of pictures that it then has to generate thumbnails for (app specific, not all will actually make thumbnails), scripts that attempt to do a LOT of work at once such as updating dozens of posts with new information, etc.
It is -not- visitor-count based. I've had sites with 0 visitors cause it because of a plugin that wasn't coded right, and others are caused because they happened to get 1,000 visitors within the same 60 second span, and their site wasn't optimized to handle this many. It really does depend on the script - some are designed for thousands of users without a problem, others only a few. EyeOS is a good example of ones that can't handle many users on free hosting - EyeOS is a cloud computing platform that was actually designed to be one of the only things running on the server, not alongside a few thousand other accounts worth of websites.
HRU is also -not- permanent. It can be unsuspended manually from the account panel, or by a mod if something goes wrong.
As for Elgg being allowed, it is, but from my own attempts to install it, it looks like the most horribly coded piece of script I've actually had the displeasure of using, even rivaling the horrible coding of my own malware scanner. The very first attempt I had with it resulted in a 404 for the install script, even after following the very specific directions I was granted from Elgg. Turns out they had a typo in their own installer which prevented it from installing properly. Not the best of signs for "good coding" when that same error remained in their public install for over a month before I gave up.
Edit: Forgot to mention, I probably could have fixed the typo in the installer and had it work, but if the installer has a major mistake like that, I'm a bit terrified of what -else- might be wrong.
