What kind of performance are you seeing with/without SIMD enabled?

From https://github.com/Lulzx/zpdf/blob/main/src/main.zig it looks like the help text cites an unimplemented "-j" option to enable multiple threads.

There is a "--parallel" option, but that is only implemented for the "bench" command.

I have now made parallel by default and added an option to enable multiple threads.

I haven't tested without SIMD.