FreeArc has different results on a different CPUs? Please explain.

[allure]

(I already posted this on official FreeArc forum, but it seems to be dead, no views, no replies...)

Really strange thing. I have two machines:
Linux (Debian), E7200, 2GB RAM, 1TB HDD
Windows7 64bit, E8400, 6GB RAM, 1TB + 0.5TB HDD

Under Linux I have Wine, so I am using exactly same, latest version 0.666 of FreeArc (http://freearc.org/download/0.666/Fr....666-win32.exe).

My Windows machine is always better than Linux. How is it possible? I make archive with exactly same content (sometimes just one file), exactly same settings (always Ultra, self-extracting executable) and I have different results! For example:
Windows 5700MB -> compressed to 3970MB
Linux 5700MB -> compressed to 4080MB

Windows 1000MB -> compressed to 667MB
Linux 1000MB -> compressed to 697MB

Is it CPU-dependent? When I buy Intel Sandy i7 2600k my compression results will be better?

[m^2]

FreeArc memory usage depends on how much of it your system has.
Also, there might be some multithreading related differences, more cores = weaker with the same settings.

[Bulat Ziganshin]

in ultra compression, you deal with lzma 2-threaded code. it doesn't have stable compression due to threading issues

[allure]

Thanks for replies. It's more clear now.