Sylvain Hubert schrieb am 04.11.2020 um 22:10:
> On Wed, 4 Nov 2020 at 21:32, Wolfgang Schuster 
> <wolfgang.schuster.lists@gmail.com 
> <mailto:wolfgang.schuster.lists@gmail.com>> wrote:
>
>     4. it performance issues and leads to a noticeable performance drop.
>
>
> This sounds a bit surprising, since intuitively it takes no less 
> effort to deal with the registered key than to determine that a key is 
> not registered.

There was never a real test for the performance but when you enable the 
checker in the example below (which works only with LuaTeX) the second 
list is slower.

% engine=luatex

\starttext

\testfeatureonce{10000}{\getcheckedparameters[test][xx][a=b,c= d, e = f]}

\enablecheckparameters

\testfeatureonce{10000}{\getcheckedparameters[test][xx][a=b,c= d, e = f]}

\stoptext

Wolfgang