Probably little difference performance-wise on such a small dataset; but it could make a notable difference if the dataset is large:

#! perl -slw
use strict;

my @bits = (
  1, 0, 0, 0, 0, 0, 1, 0,   # A / 0x41 / 0b01000001
  0, 1, 0, 0, 0, 0, 1, 0,   # B / 0x42 / 0b01000010
  1, 1, 0, 0, 1, 0, 1       # incomplete byte
);

my $data = '';
vec( $data, $_, 1 ) = shift@bits for 0 .. 8*int( @bits/8 ) -1; ## corr
+ected for complete bytes

print $data;
print @bits;

__END__
C:\test>1136846.pl
AB
1100101
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