If you run a concrete5 site (also with a lot of pages in it), you should clear the concrete5 cache from time to time.
This simple job does it as a "concrete5 job" - which you can run via a cronjob for example.
How to Run
1. Go to Dashboard - System & Settings - Optimization - Automated Jobs
2. Find a job named "SCALA Clear Cache" and click "Run".
3. Now the concrete5 cache will be cleared.