Why are my IIS Logs indexing more slowly than other kinds of logs?

[vinaykata]

What is the behavior of IIS logs different than regular logs.

Splunk is lagging a lot of time to index IIS logs while other logs are indexing as soon as they have generated.

My IIS Logs Inputs stanza

[monitor://E:\IISLogs\W3SVC*\*.log]
disabled = false
sourcetype = iis
index = weblogs
ignoreOlderThan = 1d
initCrcLength = 1024
crcSalt =