Why are Mac OS X aliases so large? They’re huge! I’ve seen sizes from 1MB to 5MB for a single alias file. Back in the System 7 days, they were mere bytes in size. Their functionality hasn’t significantly ¹ changed since then.

I poked around an alias file (with the help of xattr, DeRez, and GetFileInfo) and found the answer: they’re storing icons in there now.

Twice. Once in the data fork of the file and then once in the resource fork of the file.