Single core vs dual core benchmark

* WinZip's default compression settings "Legacy compression (Zip 2.0 compatible)
** WinZip using "Optimize for maximum compression (Use best method for each file type)" switch
*** by PeaZip's default, ARC includes recovery records

Results: single core vs dual core

Switching form one to two cores brings, as expected, little or no speed advantages for single threaded tasks, with speed ratios fluctuating near 100%; in real world conditions, however, a multicore CPU has the advantage of free cores ready to accept other tasks in the meantime, which results in more fluid system operation and less probability of slowdowns for each process.
The compression is completed in similar times on single and dual core systems for WinZip's ZIP compression (legacy, optimized and PPMd) and PeaZip using QUAD and LPAQ5 compression.

Conversely, multithreaded tasks shows noticeable speed increases on a dual core system.
WinRar's RAR compression run in 71-87% of the time switching form 1 to 2 cores, but biggest speed increases are shown by PeaZip using BZIP2, ZIP, 7Z and ARC formats, running the same task in 51-59% of the time switching to dual core.
Of course, scalability of performances on multicore environments depends on the maximum number of threads a compression algorithms can support, and how efficiently they are balanced, so those results should not be automatically extended to higher number of cores before further testing.

This benchmark compares compression ratio and speed archiving files of multiple types, using WinZip (with ZIP format), WinRar (with RAR format) and PeaZip (with multiple archive formats).
7-Zip is not included in this benchmark since 7Z, BZ and ZIP compression in PeaZip is based on standard, proven and reliable 7-Zip componets, so benchmark results for those formats would be closely equivalent in PeaZip and 7-Zip.
Programs, unless differently specified, were tested using default, out-of-the-box compression settings for the selected format.
"Speed and compression ratio benchmark" table contains results of tests performed on a dual core CPU, which allows multithreaded applications to take speed advantages over single threaded ones.
Results are grouped in three categories featuring similar compression ratio (lower %, better compression):

• first group contains results for archive types using algorithms oriented to light and fast compression;
• second group balances speed and good compression ratio;
• finally, third group is oriented to achieve maximum compression.

"Single core vs dual core benchmark" table compares speed results of same tests (grouped as in the first table) using one and two cores, and showing the % of time spent to perform the same task with multithreading (lower, more efficient multithreading).

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