diff --git a/man/man4/zfs.4 b/man/man4/zfs.4
index 539a309eac7d..a88d6f78fdda 100644
--- a/man/man4/zfs.4
+++ b/man/man4/zfs.4
@@ -1781,8 +1781,11 @@ all objects in the directory it checks, even if it's just
 looking for a single object.
 Setting this to a non-zero value disables that prefetching for directories
 with a greater size than that value.
-Disabling it for large directories can greatly lower CPU usage on NFS servers
-where directories have a very large number of subdirectories.
+Disabling prefetch for large directories can greatly lower CPU usage on NFS servers
+where directories have a very large number of subdirectories. 
+Consider setting this parameter if your primary access is via NFS, you have
+unusually high CPU used by nfsd processes, and arcstat shows very high metadata
+read rates compared with other activity.
 Directory size in this case is the size returned from calling
 .Sy stat
 on the directory (stat.st_size).