A couple of things looking at this would lead me to access patterns for the underlying objects.

I would do the inner joins first and the the outer joins.

You also have a join on a view which may be accessing several more tables.

Is there any way you could add a where clause to the first subquery (not the innermost subquery).

Also, could you provide DDL and sample data so people could reproduce your issue? An execution plan of the first query would prove most helpful here. I imagine there are plenty of scans and potentially locks happening in this query (don't believe everything you have heard about the NOLOCK hint - NOLOCK is usually a bad thing).