Hello
Half of the following example characters will cause the slowdown: –,
¥, Ń, Ł, Ǎ, Ǟ. I attach a script that does ${...///} substitution. It
is very slow for some chars and very fast for others. How to explain
and hopefully fix this?

Example script result:

( out_array=("${str//(#bi)wfeiwj/a}") ; )  0,02s user 0,00s system 97%
cpu 0,017 total
( out_array=("${str//(#bi)wfeiwj/a}") ; )  0,89s user 0,00s system 99%
cpu 0,890 total
( out_array=("${str//(#bi)wfeiwj/a}") ; )  3,70s user 0,01s system 99%
cpu 3,712 total
( out_array=("${str//(#bi)wfeiwj/a}") ; )  5,73s user 0,01s system 99%
cpu 5,743 total

Best regards,
Sebastian Gniazdowski