proforg@toad-pc:~$ cat 100bln.txt | wc -l
100000000
proforg@toad-pc:~$ time cat 100bln.txt | awk '/200000/,/800000/ {print}' >/dev/null

real	0m25.079s
user	0m24.654s
sys	0m4.025s
proforg@toad-pc:~$ time cat 100bln.txt | awk '/200000/ {f=1} {print} /800000/ {f=0}' > /dev/null

real	0m35.815s
user	0m35.404s
sys	0m6.764s
proforg@toad-pc:~$ time cat 100bln.txt | perl -ne 'print if(/200000/ .. /800000/)' > /dev/null

real	0m42.575s
user	0m42.292s
sys	0m3.868s