Loaded PDL v2.088
pdl> $x = zeroes byte, 1e9
pdl> $a = copy $x; set $a,  0, 1
pdl> $z = copy $x; set $z, -1, 1
pdl> help vars
PDL variables in package main::

Name         Type   Dimension       Flow  State          Mem
----------------------------------------------------------------
$a             Byte D [1000000000]         P          953.67MB
$x             Byte D [1000000000]         P          953.67MB
$z             Byte D [1000000000]         P          953.67MB
pdl> with_time { print $x-> any, ' ' } for 1..3
0 783.335 ms
0 749.517 ms
0 756.531 ms
pdl> with_time { print $a-> any, ' ' } for 1..3
1 0.103 ms
1 0.091 ms
1 0.092 ms
pdl> with_time { print $z-> any, ' ' } for 1..3
1 748.246 ms
1 741.717 ms
1 739.352 ms
pdl>