The diff command counts faster than ∂/∂x

[hp-zl]

When I type "diff(Σ((-1)^(k+1)/k^x,k,1,20),x)" I get the result after about 4 seconds (appendix 1).
When I type "∂(Σ((-1)^(k+1)/k^x,k,1,20),x)" I get the result after about 3 minutes (sic!) (appendix 2).

CAS Mode. Firmware: 2.1.14730. HP-Prime G2.
CAS Settings. Simplify: Maximum ("Minimum" gives worse results).

The time() command probably does not take into account the formatting time of the result and its display, but the difference is apparent: 0.7 s vs. 29 s (Appendix 3).

Regards.