A latch wait is a delay associated with the latch, and is often caused by the I/O system not keeping up with requests so it is taking a long time to get pages from disk into memory. Buffer latch contention is one common reason for long latch waits.
If you view the number of patch latch waits then you can see where and when there are large number of waits. Accurate information from regular readings will help you understand and address latch wait problems.
Gail Shaw, Microsoft Certified Master: SQL Server 2008, MVP, offers some advice on dealing with latch waits. Large numbers of PAGEIOLATCH “could be because there are non-optimal queries or indexes and hence more reads are requested than actually necessary for the workload. It may also mean there’s latency in the IO subsystem. Solutions here include tuning queries or optimising the IO subsystem.”
Idera’s SQL Diagnostic Manager offers fine-grained data on latch waits, including page and non-page wait types. This kind of detailed data greatly simplifies the process of diagnosing latch wait issues.