View performance depends on different factors including the time taken to update the view, the time required for the view update to be accessed, and the time for the updated information to be returned. The file system cache, frequency of updates, and the time between updating document data and accessing (or updating) a view, all impact performance.
Index queries are always accessed from disk. The Couchbase Server does not keep indexes in RAM. However, frequently used indexes are likely to be stored in the file system and used to cache information on disk. You can increase the RAM available for the operating system by increasing your file system cache and reducing the RAM allocated to Couchbase Server from the total RAM available.
Consider keeping some RAM reserved for your operating system to allocate to file system cache, or consider increasing the RAM allocated to file-system cache. This, in turn, helps keep space available for index file caching.
View indexes are stored, accessed, and updated, completely independent of the document updating system. Separate systems also mean that the performance when retrieving and accessing the cluster is not dependent on the document store.