It would be awesome if 7-zip archives supported LZO compression just as well as LZMA.
The UCL compression can also be used, which is very similar in that it is blindingly fast and needs no RAM for decompression.
In the example programs for for LZO and UCL, the block size is limited to 1MB and 8MB, respectively. There's no point in this for 7-zip, 192MB would be ok if you have the RAM.
The licences of lzo and ucl is GPL and incompatible with the current 7zip license.....
igor seems to hesistate to include this compression algorithm for some reason... this topic have been discuss several time already...