Indexing Service is no longer supported as of Windows XP and is unavailable for use as of Windows 8. Instead, use Windows Search for client side search and Microsoft Search Server Express for server side search.
The MaxWordListIoDiskPerf entry specifies the system I/O threshold above which indexing (word-list creation) is delayed when disk-performance counters are enabled.
|Range:||1 - 100|
The value of the MaxWordListIoDiskPerf entry is enabled only if counters in the DISKPERF.exe process are enabled. When the disk-performance counters are enabled, the value of this entry is used instead of the value of the MaxWordlistIo entry.