If your core router’s configuration has more then 5000 lines, issuing a show run is not too fast. For example on our 7200 with NPE-G1, it can take up to 5sec. I don’t like waiting, so I was happy, when I found the “Configuration Generation Performance Enhancement feature”. The configuration is very straightforward:
parser config cache interface
But what does this feature do? Cisco says:
Until the Configuration Generation Performance Enhancement feature was introduced, NVGEN always had to query the entire system and could generate only a total configuration. The time required to process the running configuration creates performance problems for configuration management, because completion of the NVGEN operation can take many minutes.
The Configuration Generation Performance Enhancement feature reduces the execution time for NVGEN processes and is especially useful for managing large configuration files that contain numerous interface configurations. This feature provides faster execution of commands that process the running system configuration by caching interface configuration information in system memory, and by retrieving only configuration information that has changed.
If you are using IOS 12.3(7)T or newer, and the router has enough memory, you can speed up the things. After I configured the feature, the sh run command was ready in less then a sec.