v4.2
- Multithreaded RAR compression is enabled by default. (You can disable it with -mt1 switch.)
- Comparing to RAR 4.11, some speed gain is possible in single processor mode as well.
- Speed gain depends on data type and average file size.
- Several cores are utilized more efficiently when compressing large files.
- We had to increase memory requirements to achieve higher compression speed. General RAR compression algorithm allocates about 120 MB comparing to 40 MB in RAR 4.11.
- RAR text compression algorithm cannot utilize several CPU coresefficiently, so its performance in multiprocessor environment is much lower than for general algorithm. Also its decompression speed is much lower than in general algorithm regardless of CPU number. So we decided to disable the text algorithm by default.
- If you need maximum possible compression ratio for plain text data regardless of speed, you can enable the text compression with -mct switch.
- RAR general decompression algorithm speed is slightly improved, though not to same extent as RAR compression. RAR decompression is not able to use several processor cores, so its performance does not depend on a number of cores.
