Say we have
a | b, under what circumstances could
b slow down
b was a CPU hog, that would do it...what if
b was consuming stdin really slowly? are there other factors?
In general, if
b was using resources (CPU, disk, memory, file descriptors etc.) that
a also needed, or if
b held any type of lock on files or in databases that
a was trying to acquire, this would possibly slow down
a (or even cause
a to fail).
a process would simply block while trying to write to
b did not read what it was writing fast enough. This is, I believe, the more common scenario.