If you have tens of thousands or hundreds of thousands of source code files or if your source code is on a physical hard drive or on a network drive, creating an index is a good option.   

Click the Plus icon to create an index.

Click the X icon to delete an existing index.

Click the Refresh icon to re-create the index using the same Directories Pattern, Files Pattern, Exclude Files Pattern and Exclude Directories Pattern.

 

The Indexes drop down contains the list of indexes.  Select File Search Mode to not use an Index

 

Kellerman Software built its own indexing mechanism that is 2x to 3x faster than Lucene.NET.