Optimising BI with Distirbuted Monitoring

I am using BI with Distributed Monitoring, creating aggregations that are confined to a single site. I would like to view the aggregation for a single site.

My approach has been to create an aggregation that generates nodes based on a host search and pattern matching the site for use in the underlying BI rules. The top level aggregation are then grouped by site. I then access the aggregation for the specific site of interest.

When I have a small number of distributed monitoring sites this works fine, but as the number of distributed monitoring sites increase the BI Aggregation view appears to time out. I suspect this is because it is generating all of the aggregations before returning the aggregation for the specific site I am interested in.

Is there some way of optimising this? I was thinking of creating a view that filtered on site and only created the aggregation for the site of interest. However, I cannot find a way of creating an aggregation that is filtered by site. Is there an approach to achieving this?

I am using CEE 1.5.0p21.cee.