Is it possible to disable verbose in the middle of running?

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http://unix.stackexchange.com – I am running a program fls (from the Sleuth Kit) with option -v for verbose mode. However it takes too long, and the program is still running since yesterday. I guess it will run faster without verbose mode, but I am not sure how long it takes to finish running and whether it is worth to stop and rerun it without verbose. so I wonder if it is possible to turn off verbose mode in the middle of running and resume the running after that? Thanks! (HowTos)