### About Cython and the main Sage commands

I read the "How to import some commands?" and "Importing sage functions into cython?" topics, so I know how importing new commands in Sage and also under %cython.

I found that main commands like "factor" or "identity_matrix" which are automatically available in Sage are not under %cython. Then, it's necessary to add the lines:

"from sage.rings.arith import factor"

"from sage.matrix.constructor import identity_matrix"

**Questions**:

- Why the main commands are not automatically available under %cython ?
- Is there a line importing directly all the main commands under %cython ?
- Or, is it a good idea to improve the Sage software so that it works directly ?

I read also that such imported commands are not "cythonised" (and so not 100 times faster).

- Are there cythonised equivalents of all the main commands ?
- If not, is there a project to cythonised all the main commands ?
- Why Sage does not use directly Cython ?