Web capacity

Is there a capacity limit for items being posted on our web-site?  If so, what are the limitations?

In my 'personal space' I have placed some files which are not for general use at this stage - They are half-baked documents or data that needs to be worked on.  Basically I am using the site as a storage to back-up my files relating to this project.  is this okay, or is there a capacity problem in doing this?

At times the downloading of the site is very slow - is this because we have put too much on it?

I do not know what the limit is for storing data but I would expect there is a need to restrict our storage to data that is relevant to the project and available to share with the team. I would not recommend that all our photos are stored unless we expect the team to use them in the research.  I would also like to have a condensed way to store spreadsheets but I still need to work with Win on this one.