cython vs golang for resource intensive tasks

my question stems from an older question which I asked a while ago. now the there is consensus among team to explore using cython or golang or something better which has good concurrency support. we have some python custom auth module which we would like to reuse.

so my question is,

  1. what language in your opinion is suited for the task given at hand?
  2. what other languages modules are available where we can use existing python custom auth?
  3. does language choice really matter?