Exhaustive search should work for any dictionary. (The 10 secs doesn't include the sort, but it could use a high watermark.):

#! perl -slw
use strict;
use Time::HiRes qw[ time ];

sub uniq{ my %x; @x{@_} = (); keys %x }

my $start = time;

my @lookup = map{
    my $bits = pack 'C', $_;
    [ grep vec( $bits, $_, 1 ), 0 .. 7 ]
} 0 .. 255;

my %dict;
while( <> ) {
    chomp;
    next if length > 8;
    my $r = \%dict;
    $r = $r->{ $_ } //= {} for sort split '', $_;
    push @{ $r->{_} }, $_;
}

my %stats;
sub X {
    my( $first, $soFar, $tree ) = @_;
    if( @$soFar == 8 ) {
        my @words = uniq map {
            my $r = \%dict;
            $r = $r->{ $_ } for @{ $soFar }[ @{ $lookup[ $_ ] } ];
            exists $r->{_} ? @{ $r->{_} } : ();
        } 0 .. 255;
        $stats{ join '', @$soFar } = \@words;
        return;
    }

    for( $first .. 'z' ) {
        next unless exists $tree->{ $_ };
        X( $_, [ @$soFar, $_ ], $tree->{ $_ } );
    }
    return;
}

X( 'a', [], \%dict );

print time - $start; <STDIN>;
printf "[%d] %s : @{[ @{$stats{ $_ }} ]}\n", scalar @{$stats{$_}}, $_ 
+for
    sort{ @{ $stats{ $b } } <=> @{ $stats{ $a } } } keys %stats;


__END__
[ 7:09:30.87] C:\test>1056884-calc 2of12inf.txt
10.4807748794556

[346] aeinprst : nape tars pets ape panties taper inept nastier print 
+airs spinet sniper pane rants pint peat spear terns tears
trains reps earn tines paints napes ate strep rest repaint ti inapt ri
+nse ripest astir priest neat part nets pans retina apes 
tarps reaps nip rain tern res sip sprint instep sear inters in prints 
+ires erst parent snip re astern satire praise stein pirates
pirate pertains tan tar pie par tis nite ant apter pa ants rites ranis
+ rite eta as pastier rents nit ties pastern rate sapient 
strip pants pits apt pent snipe niters ran pate tsar stain pints panie
+r spirea rapines tapers repast irate pars span pairs tens 
raps ripen stair tarn tans retsina tin rips pies inert eats reins ear 
+esprit aster rapes pin tarsi sera neaps rani step rein resin 
inter piastre stria painters sprain neap tripes tires raise tier en st
+ern parents pas ares sari pert satin sine nitres ripens tape
prates striae retain arts pet ani sat tare pertain insert reap pit pra
+te pea trap antsier pantie sterna tries rasp east pen spit 
sit arise naps tire tea pares pat snare stir spar pine rap tares is pa
+n rant earns pant art it painter sate pear tips pens rep pitas
tarp penis aspen antis teas nips tap aspire piaster traps past pier er
+a ears asp sane star seat entrap rip snit siren sin nae pins
spare tapes stare niter spate sitar rent prise taps anti trip trips ti
+ns spire ens tarns spent traipse antes tripe rise tapir tip
pest peas nest sent its sir pries retains anise rat pates pare rats tr
+ain saner pita eat nitre spat parse tapirs tiers ten risen 
nears sap spite set stripe sprite paniers sire strap tie sea septa pis
+ site psi eras repaints an pain paste ripe ire net entraps 
nits pair apse pains rates rapt per saint near paint rains spin strain
+ etas snap pines rapist rape are rapine sepia pantries spine 
peats tear at parties pi ante sprat retinas inset spa arisen ins parts
+ nites tine piers panes pats nap pears air
[344] aeilprst : liars tars platies pets ape taper lairs airs lire lit
+er ails peat spear plies palest tears lets lest reps ate 
strep rest lips leis slate ti ripest astir lie priest seal part apes t
+arps piles reaps trial plate res sip paler litres sear 
retail ires erst rails salt plates re satire praise pirates pirate lea
+ liras tar pie retails pleas par pleats tis apter pa 
realist pelt rites peril alters rite relit stale eta earls as litre pa
+stier lies trails ties rate strip pits apt petal pate 
list tsar spirea tapers petals repast irate pars plea pairs pleat stap
+ler raps stair saltier lit pales tali alert rips spilt 
pies eats laser ear peal slit esprit aster rapes tarsi sera ales slip 
+alit spelt step alter piastre silt stria tripes tires 
raise liar tier leapt tiler teals pas ares sari sale pert tape prates 
+pal striae riles sail alp plats arts pet plait sat tare 
reap pit late pails steal prate least pea tiles trap tries slier rasp 
+sepal pastel east spit sit arise alps tire tea pares pat 
rial stir spar laps later rap tares is la rials ilea leas staler alert
+s art it last sate ale aisle pear tips leaps rep pitas 
tarp trail lept tile stile teas tap aspire piaster teal traps past tai
+l pier split era ears asp star seat pile rip spare rile 
tapes stare spate sitar pelts triples las prise islet lisper lepta tap
+s plaster staple trip pail spiel lair pilaster trips slat 
pearl spire lip traipse tripe rise tapir lei pale tip slept pest peas 
+tilers its sir lite pries rat pearls serial rail pates 
pare rats lapse tails pita eat slap spat pals parse plaits tapirs lisp
+ tiers lap pliers salter tales sap spite set real ail 
stripe sprite sire strap splat tie sea septa pis site psi eras plat pa
+ste ripe ire let pair apse leap rates rapt per triple 
etas perils rapist rape liters lira are trials spiral sepia peats tear
+ at parties pi earl peals sprat spa isle parts tale piers 
pats pears air
...
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