[GENERAL] Expensive log_line_prefix ?

[Sahagian, David]

In 9.1.x

Are there any "extra" costs to logging all this cool stuff ?

     log_line_prefix = '%m %a %u %p %c %m %v %x'

Are any of these expensive ?
Or is the only cost the number of bytes that the textual representation of 
their values take in the written log file ?

Thanks,
-dvs-