loadmeasure goes slower and slower

Hi All,in rpas 13.3.1.2
I notice that each time  do the same loadmeasuere , it takes more time.
this is the command:
loadmeasure -d /orpas_db/fase3/domain/buy/PVC2BY -measure wpvndeues,wpvndqtaes -noClean -processes 1 -defrag -loglevel warning

and these are the times:
minutes 19,4 processes 1
minutes 21,8 processes 5
minutes 19,5 processes 7
minutes 28,7 processes 1
minutes 29 processes 5
minutes 36 processes 7
minutes 31 processes 1
minutes 44 processes 5
minutes 45 processes 7

any idea?

many thanks