unicode.txt : https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt

test 1:

//var %t = $ticks | var %r = $read(unicode.txt,nw,*10FFFD*) | echo -a > %r | echo is: $calc(($ticks - %t) / 1000)

adiirc result: 0.252
mirc result: 0.531

test 2:

//var %t = $ticks | window -hj1000000 @testing | loadbuf @testing unicode.txt | var %r = $fline(@testing,*10FFFD*,1).text | window -c @testing | echo -a > %r | echo is: $calc(($ticks - %t) / 1000)

adiirc result: 0.517
mirc result: 0.187

test 3:

//var %t = $ticks | .fopen test $qt(unicode.txt) | .fseek -w test *10FFFD* | echo -a > $fread(test) | .fclose test | echo is: $calc(($ticks - %t) / 1000)

adiirc result: 0.336
mirc result: 0.688