You'll have to benchmark to see if this is more efficient: 

my %uniq; 

my $s = "ABCABCABC1231234123123ABCABCABC123TestTestTestTestTest1234123
+123123121212121212121212121ppppp";;

print for grep{ ++$uniq{$_} == 1 } $s =~ m[(?=(.+)\1{4})]g;;
Test
1212
2121
12
21
p

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In reply to Re: Capture variable length pattern when it repeats variable times by BrowserUk
in thread Capture variable length pattern when it repeats variable times by exilepanda

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