I would be surprised to see practical performance degradation in uncompressing executable code before jumping to the program on today's machine. The largest binary in my /usr/bin/ is 50 megabytes. On the other hand, for very, very large binaries it's probably faster to decompress in memory rather than load all the bits from disk.
Further, most executables aren't static these days. (I often wish they were, though!). What type of binaries have you got, and are they really so big that it's worth the hassle to compress them just to save disk space?
Just interested.