M: aDO ( a u -- ) D=A A=@P @P+D DO ;
: space ( a u -- )   u!  a!
0x100 ad] 0 nd! 0x100 ad1] 0x100 asd] 0. d! n! 0x100 asdm] 0 nm!
0x40000   ap] 0x20000  asp] 0. p! m! 0. max! t! 0 maxg!
sd( a u  aDO 1 I C@ ad + C! LOOP ad 0x100 aDO I C@ IF I ad - ad1 nd + C! nd 1+ is nd THEN LOOP )
noBL?( is t t 0xFF AND d <> t 0xFF00 AND 8 RSHIFT d <> AND )
ap0( asp m aDO 0 I W@ 4 * ap + ! 2 +LOOP )
emd( aDO I C@ EMIT SPACE LOOP )
maxBL( 0 is max ap0 a u 1- aDO I W@ noBL? IF t 4 * ap + DUP 1+! @ max MAX is max THEN LOOP )
a u 1- aDO I W@ is p p 4 * ap + @ 0= IF p asp m + W! m 2+ is m  THEN
           p 4 * ap + DUP 1+! @ max MAX is max LOOP max is maxg
asp m  aDO I W@ 4 * ap + @ maxg =
IF   asdm nm + C@ 0= IF I C@ asdm nm + C! I 1+ C@ asdm nm + 1+ C! nm 2+ is nm THEN
ELSE asd  n  + C@ 0= IF I C@ asd  n  + C! I 1+ C@ asd  n  + 1+ C! n  2+ is n  THEN THEN 2 +LOOP
asd C@ is d maxBL max maxg = IF sd ( ad1 nd emd ) ELSE ( asdm nm emd ) THEN ;

T: str 23241214542365432175326526432561 ;
str space
STARTLOG
: test 100000 0 DO str space LOOP ;
REQUIRE .elapsed   G:/spf/devel/~af/lib/elapse.f
time-reset test .elapsed

Elapsed time: 00:00:00:141
Ok