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32-bit applications (such as 32-bit databases) can use a maximum of only 4 GB of memory because of the 32-bit address limitation. The Cached Quick I/O feature improves database performance on machines with sufficient memory by also using the file system cache to store data.
For read operations through the Quick I/O interface, data is cached in the system buffer cache, so subsequent reads of the same data can access this cached copy and avoid doing disk I/O. To maintain the correct data in its buffer for write operations, Cached Quick I/O keeps the buffer cache in sync with the data written to disk.
With 64-bit applications, for which limited memory is not a critical problem, using the file system cache still provides performance benefits by using the read-ahead functionality. Because of the read-ahead functionality, sequential table scans will benefit the most from using Cached Quick I/O by significantly reducing the query response time.