Conclusion
The ostensible performance improvements of a 64-bit compile are a mixed bag in the compressors tested. Those compressors which saw improvement may not even owe that improvement to the 64-bitness of the program, but rather to some other optimization (SSE2, for instance) that is part and parcel of a 64-bit compilation, but not necessarily of a stock Win32 compile.
Here’s a summary of the average change for each compressor.
| Compressor | Avg. Difference (%) |
|---|---|
| BCM | -4.525% |
| WinRAR | 1.429% |
| SBC | -17.875% |
| MComp | -5.966% |
| Balz | 29.843% |
| NanoZip | -11.684% |
| 7-Zip | 7.763% |
| BZip2 | -15.626% |
| GZip | -16.298% |
| QPress | 3.619% |