Now that we have introduced some of the underlying components of the indexing process, the performance counters that are available to monitor the health of the index become easier to understand. The following performance objects may be of interest to you:
Microsoft Gatherer server-wide counters of indexing activities
Microsoft Gatherer Projects workspace-specific counters of indexing activities
Microsoft Search server-wide counters about query activities
Microsoft Search Catalogs workspace-specific counters about query activities
Microsoft Search Indexer Catalog workspace-specific counters about the index
SharePoint Portal Server Subscriptions workspace-specific counters about the subscription service
A number of counters are ...