Home / Executable compressors comparisons: upx 3.07w vs. mpress 2.17

SumatraPDF executable is compressed with executable compressor. It makes the file smaller and faster to download. On the downside, it increases probability of false positive from virus scanners.

For a long time I’ve been using upx but I’ll probably switch to mpress since it compresses a little bit better and it’s most expensive compression -s is much faster than upx’s —ultra-brute.

Here’s a comparison using upx 3.07w and mpress 2.17 when compressing release version of r2466 (pre-release for 1.3):

4598272 uncompressed
4527104 stripreloc /b /c

2205184 upx —best —compress-icons=0h
1756160 upx —ultra-brute —compress-icons=0

1725440 mpress -s (-s : find the best compression)
1735168 mpress -s -r (-r : dont compress resources)
1767424 mpress

The last result is for StripReloc, which is not a compressor. It only removes unneeded .reloc section in exes. Mpress must already be doing that internally because compressing raw version and stripreloc’ed resulted in the same size.

There is a serious downside to executable compressors: many anti-virus program falsely report compressed executables as a virus or malware.