Hi I own a forum and currently have shared hosting as a package. How many users do you think my shared hosting package (I have unlimited everything) would cope with being online at once???
Well since there's no such thing as "unlimited everything" who knows. There are probably something in the host's Terms of Service that are going to limit your CPU usage, RAM usage, number of processes you can run, etc. There is just no way of knowing.
Most probably few hundreds of members. I suggest you to go for a good VPS plan, if your forum has more than 100 active members to avoid from getting suspended.
If your forum is new you can run it easily with shared hosting account but as the members and daily traffic increase your forum will start using more server resources. This is the stage where your host can ask you to upgrade to VPS because with VPS you will be getting higher server resources. Just having "unlimited everything" doesn't mean you can run any kind of site, but it just mean you can host a lot of stuff only if it is not using more than allocated server resources. Hope you understand it now?
We are currently hosting a forum that has a pretty big user base and do not have too much overhead with it. You should not have problems on a shared host unless you are breaking a 20 process limit.
Depend on what server your plan is located at. Normally shared hosting will only allocate around 5% of the total CPU/memory resources. Anything above that you'll get warning from them.
You are definitely going to need a better hosting plan once your forum starts to develop but shared hosting is fine while you get it started.
If you are just starting then you most likely you will be OK with a shared plan. But, if you start to get many visitors and traffic then you will want to move up to a VPS rapidly. When you have success move from shared or your forum could suffer with issues.
No need to take VPS Hosting you could even go with the cloud hosting services with your shared hosting. Your data will be available on many servers and it will reach to the visitor from nearest server located. So by this you could host it without any problem and your traffic could be even in thousands.
You can continue with your shared hosting and once you feel that usage is becoming high you can opt for better shared hosting or vps.
It all depends upon the configuration of server, the more powerful the server will be the more users you will be able to compensate at a time Ask your hosting provider about the configuration of the server, it would give you rough idea about how much user you can compensate at a time