grep -i excessively slow

[Paul Rubin]

I have a text file of about 40 megabytes.  If I grep for "hello" (file
is in ram cache) on my p3-750 it takes about 0.1 cpu seconds:

    address@hidden time grep hello myfile >/dev/null

    real    0m0.226s
    user    0m0.111s
    sys     0m0.111s

Now I do the same thing with grep -i, and it takes 200 times longer:

    address@hidden time grep -i hello myfile >/dev/null

    real    0m23.437s
    user    0m22.133s
    sys     0m0.162s

This makes me think that grep is doing something really dumb when -i
is used.