The community currently runs 2 full hardware servers. One server runs all of the TF2/Source Engine servers, teamspeak, and mumble. That's 14 different services running on an 8-core server with 12GB RAM. It's not *pegged*, but there certainly isn't room for anything else. The other server is our webserver. It runs the web service that runs our site, the database server, and the minecraft server. This isn't pegged, but we've had spikes in web traffic here and there that pop the load up.
What you don't understand is that we know how to do our jobs. We are in the positions we are in for a reason. Questioning VintagePC on how things work is not helping anyone. When we shut down the Tekkit server, I immediately devoted all of the RAM that was for Tekkit over to FTB. This only helps to a certain extent because of the following reason:
A: Minecraft is written in Java
B: Java is a programming language that makes itself OS-independent through the magic of making a virtual server with its own mini-operating system within your operating system (Inception anyone?)
3: The virtual machine they run is only capable of utilizing a single CPU thread.
C: This makes Minecraft a bloated, buggy, memory-leaky piece of shit that eats the fuck out of resources, except for CPU because it's too mentally handicapped to know what to do with all of the CPU you offer to it.
F: Take that bloated, buggy, memory-leaky piece of shit, and add 45-ish different mods that were written by different people that don't give a crap about how their mod plays with everyone else's mods.
THIS is what we're trying to maintain on our server. This is what is currently using an entire 4GB of RAM at any given moment, and is trying to use 140%+ of a single CPU core.
NOW. Take all of this information, and consider this. This server has 2x 4 core CPUs with hyperthreading. If we were capable of giving it more resources, we would. It will use 100% of the RAM I give it regardless of the amount. I've given it 6 and even up to 8GB RAM, and it didn't increase performance, so I put it back to 4GB, which is where the performance leveled out. It's using every bit of resources that it knows how to use. If we could make it run better, we would. If we could dump more resources at it, it would have been done already. We *HAVE* the resources, it doesn't help anything.
And no, I have no idea wtf you mean when you say it only effects 1 person. When that person logs into the server, it is not their minecraft client that crashes. The console on our server, the part that everyone's client connects to, throws a big ole capital-letter "JAVA FATAL EXCEPTION ERROR: I'M A BIG PIECE OF SHIT BECAUSE JAVA" and dies. It passes on. It ceases to be. It rings down the curtain and goes to join the choir eternal. It is an ex-server. Then one of us (the server admins) has to log in and restart it so you can connect again and play.