Hi,
It seems an odd question, to be concerned with the hidden .svn folder. Perhaps it's exactly the question you need to consider. However, previous experience makes me wonder if there's another possibility.
As Daniel states, the .svn folder keeps pristine copies of the checked out files. Consequently, the .svn shouldn't really be much different in size to the files that need to be checked out for development. That is, the .svn is only doubling the required storage space [required for development] which doesn't seem very significant.
However, I've found that users that are more familiar with other VCS tools (e.g. git) can sometimes checkout the full repository rather than only the element that's required. That approach could significantly increase the local space required for typical development - both for the standard checked out files and the hidden .svn folder - by a much larger factor.
For example, a typical Subversion repository might have a structure as shown below:
/
/trunk
/branches
/BR-issue1
/BR-issue2
/BR-issue3
/tags
/ver-1.00
/ver-1.10
/ver-1.20
/ver-2.00Typically, a developer will only need to checkout a simple element (e.g. trunk OR BR-issue2 OR ver-1.20). This important thing to note here is that the checkout of a single element will require significantly less storage than a checkout of the full repository.
Now, Subversion doesn't impose any particular structure and so the structure can change from repository to repository. Consequently, Subversion will happily let a user checkout the full repository, even where it isn't the appropriate action. However, a full repository isn't normal, nor what is probably required. Since a distributed VCS tool (e.g. git) clones the FULL repository, users coming from those systems can sometimes believe that the checkout has to be done that way. That isn't the Subversion approach. That difference of operation would increase the size of the checkout and the hidden .svn folder.
If this is the issue, then the solution is to adopt the Subversion practice of only checking out the element that's required (e.g. trunk OR BR-issue2 OR ver-1.20). I'm sure that there are good books or online guides that describe typical usage of Subversion.
As I said, this might be irrelevant to your question. If so, sorry about that. However, perhaps this is the cause of the slightly unusual question. In that case, it seems worth mentioning. At the very least, it captures the possibility for others that might search and find this thread.
Hope this helps.