There is some loss of performance?

var cfg_file := ReadConfigFile( ":Books:itemdesc" );

or

var cfg_file := ReadConfigFile( ":*:itemdesc" );

Which you think is the best?

ReadConfigFile( ":*:itemdesc" ); -- Will read all itemdesc.cfg from all packages.

ReadConfigFile( ":Books:itemdesc" ); -- Will read itemdesc.cfg from ":Books:itemdesc" only.


Personally, I prefer to read only the necessary files. But it shouldn't affect your sysload if the script is not called too often like a combat script.

and if it is used for a spell?

I tested, not slow it is, has the same speed

Of course reading all cfg files is slower, but only the first time then it is cached.