I tested below on CentOS 5.10 Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz
GCC 4.1.2.

$ env LANG=C time -p src/grep -f regex.re input_lines.txt
Command exited with non-zero status 1
real 4.81
user 4.40
sys 0.09

I apply an attachment, and tested again.

$ env LANG=C time -p src/grep -f regex.re input_lines.txt
Command exited with non-zero status 1
real 4.63
user 4.46
sys 0.10

Therefore, I don't think that the patch is effective.