Are there any NFS performance tests?

Hi Xymon List:

     Does anyone know of a test script that I can add, that checks if an NFS mount is performing quickly enough?  Basically, I have a few users complaining that every once in a while, an "ls" of their NFS mounted home file systems take a long time.  I would like a xymon test that could check for that, in cases where a command (such as an ls of a file system) takes longer than "x" amount of time, display a warning or error.

Thank you,

Paul