I was not referring to snipes at me. He has been polite and helpful toward me. I was referring to the two digs at Zunzun.
Those are not digs at zunzun. He really is the only member I've ever seen with sufficiently high CPU requirements for it to be an issue, and he really does pop into threads discussing it to list himself as the exception. I'm surprised he hasn't here yet, especially since he really does have experience with using a lot of CPU power on a linode.
But in this case I did need to know cpu power. Linode have this in their terms of service
Misuse of System Resources: Intentional misuse of system resources, including but not limited to employing programs that consume excessive network capacity, CPU cycles, or disk IO.
That's more of a CYA kind of thing; each host box having eight cores (at least, that's all we know about, they could be quad CPU boxes, Linode won't tell anymore), and each linode having only four virtual threads, no one linode can completely hose a host. If it's a problem, Linode would let you know, and resizing a linode is very painless, it takes only as long as the time it takes for the linode manager to copy your disk image to a new host (it's all automated).
Network capacity tends not to be a problem either. There's a default outbound cap of 50 Mbps upstream, which they'll raise if you can demonstrate you need more. If you're using a ton of network capacity, you're very likely paying extra for it, so they're fine with that; if you are sending out 100Mbps constantly all month long, but you're paying the ~$3k in extra bandwidth each month, they're not going to complain.
Disk IO is the only thing that is a concern, really; as far as we know, linode hosts have four 15K RPM SAS drives in RAID 10, so there's a lot of IOPS to go around, but they're not SSDs, so it's impossible to truly schedule and manage IO like you can CPU usage. The rule of thumb that Linode has given in the past is, if you're averaging under five digits (as in, under 10k for IO in the linode manager), you're fine. If you're averaging in the five digits, you should keep an eye on it.
So I wanted to know what size of linode to go for so as not to degrade the performance of other nodes on the same box.
Don't worry about it, as I said, you can't degrade the performance of other nodes on the box with CPU usage (and they'll let you know if you need to upgrade later). Start with what you think you'd most like to pay (or size it based on RAM), and if it's not fast enough, bump yourself up to a larger linode (takes just a few minutes, entirely automated) to get a bigger guaranteed share of the pie.
My application is a personal hobby thats why it is not going on any work servers. It is a browser based wargame that has at least 50 concurrent users offpeak and 150-200 users during peak hours at weekends. It does a lot of computational work so you can see how it is cpu intensive.
Thanks to the answers here I know what size linode best suits me for this particular app.
Don't be afraid to experiment, since changing the linode size is painless; a lot of people overestimate what kind of Linode they need (or just don't know how to tweak their setup properly, and I'm not saying that this applies to you), and end up paying for more than they need. I mean, Apache's default config under moderate load can easily consume 8GB or more of RAM, but you can probably handle that same amount of load on a 512MB linode with some reconfiguring (since Apache's default settings are completely insane and irresponsible). So users who just leave it as-is end up paying for a ton of RAM they don't really need. I'm ranting at Apache, now, not you