The execute the transaction code KE24 is very slow

The execute the transaction code KE24 is very slow when run for the 1st time a day (regardless of the user, in the QAS and PRD).
Example: Even consulting a single document in the background, it took 30 minutes to complete.
Note: After completion the first run, the next are run too quickly even online.

Does anybody knows the why?

Thanks, Fabiana