git blame vs git log --follow performance

Hi.

Is there something that can be done about improving git log --follow -- <file> performance to be nearly equivalent speed to git blame -- <file> ?

The overall cpu time taken for these 2 commands that track individual file history can be quite different.

	git log --follow -- <file>
and
	git blame -- <file>

It seems that there can be a couple orders of magnitude delta in the overall time taken.

For instance (using the Linus' linux kernel git):

$ time git log --follow -- drivers/firmware/google/Kconfig > /dev/null

real 0m42.329s user 0m40.984s sys 0m0.792s

$ time git blame -- drivers/firmware/google/Kconfig > /dev/null

real 0m0.963s user 0m0.860s sys 0m0.096s

This particular file has never been renamed.

Looking at the output on screen, there does seem to be 25+ seconds of cpu time consumed after the initial (last shown) commit that introduces this file.

Perhaps adding a whole-file rename option to the "git log" history simplification mechanism could help?

Thoughts?