title: How to avoid multiple cache clearing for one edited record?
body: <p>We have the problem:<br>
  An editor edits a news record, which contains 8 images. The installation is configured to clear cache of 4 pages if a news record is edited. (<code>TCEMAIN.clearCacheCmd = 12,13,14,15</code>)<br>
  But instead of one clearance of cache for those 4 pages, each clearance occurs 9 times: one for the news record, and one for each (unchanged) referenced file. These multiple cache clearings take very much time and it even occurs that an error is thrown.</p>
  
  <p>How can we avoid the multiple clearing of the cache for the same pages?<br>
  Can we speed up the cache clearance with additional indexes?<br>
  Can we use hooks to clear those page caches just one time?</p>