high console cpu on /interface monitor-traffic once

I am running script that uses /interface monitor-traffic $ifname once. I need current values of tx rx. When command ends there is console output and profiler shows up to 30-50% cpu usage on console (rb2011l-in).
Is it cpu-intensive command or console output consumes cpu? How could i decrease cpu usage?

I have looked through wiki trying to find if policy can restrict console output and did not find anything. BTW only old policies are decribed in wiki.

Are there any ways to limit cpu used by script(s) ?

this is not considered an issue. Unless you do this non-stop and peg CPU at 100% for period of time. Consider that CPU is still most expensive part of the device and usage you name only shows that you finally get back what you have paid for,similar to CPU in your PC.