The table below shows the results of using different compression methods and levels with an example file (the file text8 was used) and SyncBackPro. The example file is text (not binary) and has an uncompressed size of 100,000,000 bytes.

All the compression methods (except for BWT) are compatible with various compression utilities, e.g. WinZip, 7zip, WinRAR, etc.

Deflate has the worst compression, but it is fast. However, if you are using SyncBackSE or SyncBackPro, then you should choose Deflate64 instead of Deflate as the performance is very similar but the compression is higher with Deflate64.

XZ and LZMA2 have the worst performance but the best compression. It is probably better to choose LZMA instead, except if you are using the highest compression levels, as LZMA requires a large amount of free memory. Like Zstandard, XZ can only be used with multi-zip, i.e. each file goes into its own Zip file. 

Zstandard has the best performance. Choose this if performance is important, but note that it can only be used with multi-zip, i.e. each file goes into its own Zip file. ZStandard has been implemented with performance, and not high compression levels, in mind. If you choose ZStandard then it is recommended to use a normal or lower compression level.

If you want to encrypt the filenames within the Zip file then you should use BZip2 instead of LZMA2 unless performance does not matter or compatibility is a requirement.

LZMA2 compression was introduced with SyncBack V11. XZ and ZStandard compression was introduced with SyncBack V11.2.5.0.

Important: High compression levels, especially when used with LZMA, use very large amounts of memory. You may experience Out of memory errors with some files, especially larger ones. To reduce memory usage you must reduce the compression level. Also, consider using the 64-bit version of SyncBackPro/SE.

Compression MethodCompression LevelSize of compressed file (KB)
DeflateLowest (1)38,560
DeflateNormal (5)32,890
DeflateMaximum (9)32,288
Deflate64Lowest (1)38,382
Deflate64Normal (5)32,304
Deflate64Maximum (9)31,341
BWTLowest (1)29,096
BWTNormal (5)26,522
BWTMaximum (9)25,776
BZip2Lowest (1)29,105
BZip2Normal (5)26,524
BZip2Maximum (9)25,777
LZMALowest (1)32,058
LZMANormal (5)23,465
LZMAMaximum (9)22,671
LZMA2Lowest (1)30,993
LZMA2Normal (5)23,468
LZMA2Maximum (9)22,675
Deflate (SecureZip, 256-bit AES encryption)Lowest (1)38,572
Deflate (SecureZip, 256-bit AES encryption)Normal (5)32,904
Deflate (SecureZip, 256-bit AES encryption)Maximum (9)32,303
BZip2 (SecureZip, 256-bit AES encryption)Lowest (1)29,105
BZip2 (SecureZip, 256-bit AES encryption)Normal (5)26,525
BZip2 (SecureZip, 256-bit AES encryption)Maximum (9)25,778
Lowest (1)
Normal (5)
Maximum (9)
Lowest (1)
Normal (5)
Maximum (9)

In regards to performance:

  • Zstandard is the fastest (if the compression level is not above 5)
  • Deflate and Deflate64 are fast
  • BWT and BZip2 are slower than Deflate and Deflate64
  • LZMA is slower than BWT and BZip2
  • LZMA2 and XZ are the slowest (much slower than LZMA)

If you are using multi-zip compression (each file is compressed to it's own file) then you can greatly improve performance by enabling multi-threaded compression and decompression (see the Compression -> Compressed settings page for the profile).

Also, reducing the compression level can make a big difference, especially with LZMA, LZMA2 and XZ compression.