"With better interface I meant that WinRAR's interface is more functional when compared with the 7-zip one, there is a lot of functionality is not working when clicking on it."
Really? I hadn't noticed that some of the functionality didn't work. Thanks for pointing that out.
Thanks also for explaining to me your need for max compression ratios and max performance for your humungous archives. Where on the planet are you? I recall when I used to work in SE Asia I had to put up with some awful telecomms infrastructures, and would often have to use a 56K dial-up link with an actual bandwidth of about 30K. That's when I started getting interested in using ZIP files - emailing out only ZIPped attachments and asking people to only email me ZIPped attachments.
Having just done some comparison between standard ZIP compression by the Win7 OS, and 7-zip, and then the 7z compression by 7-zip - I observed that there was a significantly better compression ratio in the 7z files. Now I understand why you might want to use it and why you are interested in processing speeds for those files.
When I compress document files/folders, I would only use the standard ZIP, as I need my disk-based archives to be able to be indexed/searched by the Win7 OS and by Google Desktop and it gets tricky or impossible with less standard compression methods. However, I still need to have something to help me to uncompress the various non-ZIP archives I come across. 7-zip looks OK for that purpose, so far.