[eluser]tonanbarbarian[/eluser]
that would depend on the server that it is run on ultimately
CI is one of the lightest frameworks available, so it loads a minimum of code before it actually gets to work, and if you make the effort to code things well you can make sure that a minimum of code is loaded at all time.
for example i developed an app in CakePHP (another framework) and then again in CodeIgniter. The Cake app used 5M of memory to display a page compared to CI using only 1.5M
This means my CI app should be able to handle 3 times the load of the Cake app.
But I am sure that if I did not use a framework at all, but code each page as a stand alone PHP script I could get the memory usage down to very small, maybe as low as 0.5M, but then it defeats the purposes of using a framework
As I stated to begin with it ultimately comes down to the server.
If your server has limited memory or CPU, or is a shared server that is oversold then no matter what you do you might not be able to handle the load you want.
If your server is a decent dedicated server then you should be able to handle that load or more easily.
but of course what is a "decent" server spec... I leave that up to you to decide.
