Apache, when misconfigured, can use a lot of memory. By default, it is configured for large servers - so it will use a lot of memory, but will be able to handle a lot of users. If you configure it properly, it's fine.
I added [html] and [code] tags to both of your posts - please use them in the future.
Adding it to the window object will not mean that you can access it across pages, you want to set a cookie or something.
I'm not really sure what you're asking - could you give us a context and example...