Mexxi, your experiments are quite interesting. I have one suggestion but not sure if thats what you want. You can try v4.32 of 7-zip. The deal is that later versions have increased speed at the cost of increased memory consumption. Some later versions also include tweaks of LZMA to improve compression. I better illustrate this with small test conducted on pak0.pak file from Half-Life (Gordon says hello to Shepard ). Tested on XP Pro 32-bit with 32 bit versions and
-m0=LZMA:d=128m:lc=3:fb=64:mf=bt4. Results are in form of version\resulted size\memory consumption.
Not sure if it will be the same with x64 versions but I think it worth trying. By the way I just noticed that 32-bit version of 7-zip (at least 9.07) is limited to 128 MB dictionary. That's why I love FreeARC - it allowed me to use 153 MB dictionary with bt4 match finder. Another thing is that I usually have 1670 MB of free memory under XP. I rebooted into safe-comand-promt-mode and got 1863 MB of free mem but the maximum allowed dictionary for FreeARC remained same. Why? Something related to largest address space or how it called?
v4.32 = 98 225 268 = 1 256 MB (9.1% lower)
v9.07 = 97 799 032 = 1 382 MB