serious performance issues with images, audio files, and other "non-code" data

Hi,

We're seeing serious performance issues with repos that store media files, even relatively small 
files. For example, a web site with less than 100 MB of images can take minutes to commit, push, or 
pull when images have changed.

Our first guess was that git is repeatedly attempting to compress/decompress data that had already 
been compressed. We tried these configuration settings (shooting in the dark) to no avail:

    core.compression 0   ## Docs say this disables compression. Didn't seem to work.
    pack.depth 1     ## Unclear what this does.
    pack.window 0    ## No idea what this does.
    gc.auto 0        ## We hope this disables automatic packing.

Our guess that re-compression is to blame may not even be valid since we can manually re-compress 
these files in seconds, not minutes.

Is there a trick to getting git to simply "copy files as is"?  In other words, don't attempt to 
compress them, don't attempt to "diff" them, just store/copy/transfer the files as-is?

Thanks,
  -John