How can I read lines at a fixed speed?

pv, which is available as a NetBSD package, lets you limit the rate of a pipe.

<large_file pv -L 1k | netcat …

As it turns out, pv is the perfect tool here (at least pv 1.6.0). With the -l (line mode) flag, -L limits become lines.

Simple proofs:

seq 0 1000|pv -l -L100 > /dev/null
1k 0:00:10 [99.6 /s] [           <=>                  

seq 0 10000|pv -l -L1k > /dev/null
10k 0:00:09 [1.03k/s] [          <=>