Currently, the Linux executables in pdfsizeopt_libexec_linux-v9.tar.gz are 32 bit executables.
Running 32 bit executables is still supported on most 64 bit linux distros, but there's a trend to disable this. E.g. recent kernels have a CONFIG_IA32_EMULATION_DEFAULT_DISABLED option. So it can be expected that more Linux 64 bit systems will come without 32 bit executable support in the future.
Therefore, it might be a good idea to provide the executaibles in 64 bit format.
Currently, the Linux executables in pdfsizeopt_libexec_linux-v9.tar.gz are 32 bit executables.
Running 32 bit executables is still supported on most 64 bit linux distros, but there's a trend to disable this. E.g. recent kernels have a CONFIG_IA32_EMULATION_DEFAULT_DISABLED option. So it can be expected that more Linux 64 bit systems will come without 32 bit executable support in the future.
Therefore, it might be a good idea to provide the executaibles in 64 bit format.