A cache is a special subsystem that stores frequently requested data. Without caches or caching, IIS can potentially impose three time-consuming processes on each request, which can cause poor response times. These processes include:
Reading metadata for each request, which results in a time-consuming remote procedure call (RPC) to the IIS Admin service.
Retrieving the authentication token for the IUSR_computername account with a time-consuming RPC to Lsass.exe.
Opening and reading the file.
To mitigate these time-consuming processes, HTTP.sys and IIS use caches. These caches are all enabled by default and should not require much tuning by administrators. If, while monitoring Web Service Cache counters ...