The other way is to stitch the regexes together, so that you run a single regex per line, and then sort out which field(s) you've found when you get a match. Along the lines of:

use strict ;
use warnings ;

my %KLARF_REGEXP = (
  '1.X'   =>  {
                    'LOTID'     => qr/LotID "(.+)";/i,
                    'DEVICEID'  => qr/DeviceID "(\w+)";/i,
                    'STEPID'    => qr/StepID "(.+)";/i,
                    'SLOTID'    => qr/Slot (\d+);/i,
                    'DEFECTS'   => qr/DefectList/i,
                    'RESULT_T'  => qr/ResultTimestamp (.+);/i,
                    'WAFERID'   => qr/WaferID "(.+)";/i,
                    'SETUPID'   => qr/SetupID (.+);/i,
                    'OMARK'     => qr/OrientationMarkLocation (.+);/i,
                    'DIEPITCH'  => qr/DiePitch (.+);/i,
                    'CENTER'    => qr/SampleCenterLocation (.+);/i,
              },
  '1.8'   =>  {
                    'LOTID'     => qr/LotRecord "(.+)"/i,
                    'DEVICEID'  => qr/DeviceID 1 \{"(\w+)"\}/i,
                    'STEPID'    => qr/StepID 1 \{"(.+)"\}/i,
                    'SLOTID'    => qr/Field SlotNumber 1 \{(\d+)\}/i,
                    'DEFECTS'   => qr/DefectList/i,
                    'WAFERID'   => qr/WaferRecord "(.+)"/i,
                    'RESULT_T'  => qr/Field ResultTimestamp \d \{(.+)\
+}/i,
                    'SETUPID'   => qr/Field RecipeID 3 \{(.+)\}/i,
                    'OMARK'     => qr/Field OrientationMarkLocation 1 
+\{(.+)\}/i,
                    'DIEPITCH'  => qr/Field DiePitch \d \{(.+)\}/i,
                    'CENTER'    => qr/Field SampleCenterLocation \d \{
+(.+)\}/i,
              },
);

my $vers = '1.8' ;

my $r_items = $KLARF_REGEXP{$vers} ;

my $r  = join('|', values(%$r_items)) ;
my $rx = qr/($r)/ ;

my %result = () ;

while (my $line = <DATA>) {
  ITEM: while ($line =~ m/$rx/g) {   
    my $value = $1 ;
    $value =~ s/\s*\z// ;
    foreach my $id (keys %$r_items) {
      if ($value =~ m/$r_items->{$id}/) {
        $result{$id} = $1 ;     # Worry about multiple values ?
        next ITEM ;
      } ;
    } ;

    die "Found '$value', but no match ...??" ;
  } ;
} ;

foreach my $id (keys %result) {
  print "$id = '", $result{$id} || '', "'\n" ;
} ;

__DATA__
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
LotRecord "Don't Look Back"
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
DeviceID 1 {"The Device"}
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
StepID 1 {"Staircase"} Field SlotNumber 1 {497562} DefectList
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
WaferRecord "Sandwich"
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg

Field ResultTimestamp 7 {25-Oct-1952}

Field RecipeID 3 {First catch your rabbit}
Field OrientationMarkLocation 1 {This way up}

  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
  gjhfgljhgwdchgdjlwhgjhdgsljh sg hjhg sljhg sljhg ljhjlhg sljg
Field DiePitch 3 {Beetle} Field SampleCenterLocation 4 {Gravitas}
ghcgjhcgjhghjgd sljh dsg
;kj sh;kj shkj dhk sjdh
[download]

I can think of ways to improve the inner loop, which is iterating over the item regexes -- but I wouldn't worry about that unless this is still not fast enough.

PS: incidentally, I'd look at the regexes and see if:

• you want to replace single spaces by '\s+', to allow a little lee-way.

• you can replace '.*' and '.+' by '[^?]*' and '[^?]+', where '?' is the expected terminator (eg '"' or '}' etc).

The very rough code above makes a mess of dealing with the Field DiePitch line, because the regex gets greedy !