Using "Benchmark" command you may compare performance of RAR compression algorithm on different computers.
This command generates random data, which contain specially introduced redundancy increasing load to processor and memory. Then data are passed through RAR compression and decompression algorithms and output of decompression algorithm is compared with source data. If any difference found, WinRAR reports "Errors found - Yes" in the command window. Such errors may indicate hardware problems like unreliable memory. Also WinRAR displays a size of processed data and compression speed, current and resulting, in kilobytes per second. You may use the resulting speed value to compare RAR performance in different conditions. For example, "Benchmark" command may be helpful, when you need to choose a new computer and wish to know which one will compress data faster. Only the general compression algorithm in "Best" mode with 4096K dictionary is called, all additional filters and algorithms are disabled, so it measures performance of core RAR compression on worst case like data.
Using "Multithreading" option you can compare performance of usual single threaded and multithreaded (optimized for multiprocessor architectures) versions of RAR compression algorithm.
It takes some time to fill the compression dictionary, which is empty in the beginning. Until it is done, the speed value is inconsistent, so the command window starts to display the current speed only a few seconds after activating. Resulting speed is displayed when collected statistics is enough to get an accurate result. After the resulting speed has been set, it is not changed more. Though source data are random, their redundancy level and other parameters are always the same. So this command will report practically the same current speed regardless of execution time, provided that system load is not changing.
It is not guaranteed that different WinRAR versions will report same compression speed values, so if you use this command to compare performance of different computers, ensure that you run the same WinRAR version in all tests. Also it is recommended to close other applications before starting a benchmark.
"Benchmark" command is never finished automatically, you need to cancel it manually. It does not use the hard disk, all operations are performed in memory.