Using Immutable view or Mutable view ?

I am wondering whether we should use Immutable View (like ImmutableSequentialGraph) or instead use a mutable view like ArrayListMutableGraph. The advantage of using a Mutable view is to make the graph as we parse the website. However in order to save the file or to extract any information we would need an immutable view which can be done only after crawling is complete or by using some synchronization.