HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters
ObjectCacheTTL (DWORD): Amount of time in seconds, static cached objects stay in memory (without be referenced). Default 30.
This can easily be increased to a large value like 600 (10 minutes).
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters
LogFileBatchSize (DWORD): This specifies the batch size for writing log files. The server caches the last LogFileBatchSize bytes of data in memory buffers before it dumps the current buffer and moves onto the next buffer. Default 64*1024 (64KB).
If you got the memory you can at least double this value 131072 (128KB), triple 196608 (192KB) or more.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters
ListenBackLog (DWORD): Length of the Connection Queues. Default 15.
Busy sites might set this value in the 100s (like 250).
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters
MaxCachedFileSize (DWORD): The maximum file size, in bytes, of cached
content. Any file larger then this value will not be cached.
Default: 262,144 (256KB)