This is just a remark for my experience way back 5 years ago. That time I just barely heard about 7-zip and found a monster called WinRK (still in version 2.16). I conduct a benchmark (just a little) to my amusement today.
The test file is unfortunately just one: emule.exe (damn that WinRK is too slow for my processor). Here is:
emule 0.50 : 5.49MB
WinRK : 1.25MB
Uharc : 1.65MB
7-zip : 1.68MB
WinRAR : 1.79MB
All set at best (slowest) setting, WinRK did insane deep analysis for an exe file and took 6 min. to complete! (not multi-threaded) while game warez cracker's de-facto choice UHARC is the one that better with a little time overhead. I choose Emule because it is already a composite file, have few megabytes of unicode text, dozens bitmap images and the binary itself. Zip and BZip2 result is more than 2MB.
Analysis did take important part of compressing especially in solid mode. While 7-zip and others separate executable from data file by file extension (not by actual content) then sorted based on similarity (again only by filename) this often lead to inefficiency (in compression not time) due to mis-detection unless you came up with your own filelist. WinRK took this seriously, maybe their compression method isn't much better than LZMA (7zip) but their analysis did! It has some passes where it will chop most file into more edible chunks before compressing like no others. Imagine if I had to compress the whole Gimp with WinRK! probably will take the whole night :)) on my E2160.
If you are someone with obsessive-compulsive personality disorder try WinRK! maybe version 3 have multithreaded support? (note: it's not free)