Git checkout preserve timestamp?

I often find myself in branch A, with everything checked in and compiled, wanting to look at something on branch B. I hop to branch B, look, and come back to branch A. Unfortunately, when I then do a make, files that differed between A and B will be recompiled, as well as any further dependencies.

I wonder if it would be possible or desirable to have a config flag that told git to restore the timestamps across branch checkouts in order to prevent this perturbation.

So, when git does a checkout of a branch, it would look to see which files in the current branch are changed, tuck away the timestamps for those, and switch to the new branch. On return to the former, the same would be done for the new branch, then after the changed files were restored, the timestamps would be reset.

One thing this would enable is to be able to hold the compilation products of multiple branches at the same time in the same working tree, switch back and forth between branches, and only have to compile code that you actually modify. Currently, we store compilation products in a directory that is composed of the architecture, compiler, compiler options, and so forth, among which also could be the branch name.

Anyway, just an idea I thought worth batting about.

Bill