Search Results

or try
sed 's/from\|FROM/to/g' file1> file2

# time sed 's/from\|FROM/to/g' file1> file2
real 0m0.269s
user 0m0.225s
sys 0m0.040s

# time sed 's/from/to/gi' file1> file2
real ...

I think the problem is in the I-switch. I did a couple of quick tests. On average it took 10 times longer with the I-switch than it did without. Perhaps the I switch is not necessary everywhere, or...