NFS version 3 contains an operation called READDIRPLUS. Most READDIRs are now issued as READDIRPLUS calls; for example, an ls or an ls -l triggers READDIRPLUS calls. When the ls -l commands run over version 3, the file handles and attributes are returned with the list of names in the directory. In version 2, the names are returned first, then additional calls to the server are required to obtain the file handles and attributes.
The advantage of the READDIRPLUS operation in version 3 is that an ls and an ls -l are now comparable in speed because separate GETATTR requests are not required for each file.