two similar tables - very different import speed - forum topic by TrackingDaily

I have two very similar tables, see below.  On a regular basis, I import about 300,000 records.  The original table required about 90 min to 2 hours to complete the import.  The newer table can do it in under 30 minutes.  What makes the newer table so much faster?  Is it having so many fewer NOT NULL fields in the new table?  The new table has one additional column, so it actually imports about 5% more data.  I can't really figure out any other possible differences.  Thank you.
 

/* original table -- very slow import */

CREATE SET TABLE mydb.Table_One ,FALLBACK ,
     NO BEFORE JOURNAL,
     NO AFTER JOURNAL,
     CHECKSUM = DEFAULT,
     DEFAULT MERGEBLOCKRATIO
     (
      a DATE FORMAT 'YY/MM/DD' NOT NULL,
      b INTEGER NOT NULL,
      c VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC,
      d DATE FORMAT 'YY/MM/DD' NOT NULL,
      e FLOAT NOT NULL,
      f FLOAT NOT NULL,
      g FLOAT NOT NULL,
      h VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      i VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      j VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      k VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      l VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      m VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      n VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      o VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      p INTEGER NOT NULL,
      q INTEGER NOT NULL,
      r INTEGER NOT NULL,
      s SMALLINT DEFAULT 0 , 
PRIMARY KEY ( a , b ))
;

/* newer table, much faster -- but why? */

CREATE SET TABLE mydb.Table_Two ,FALLBACK ,
     NO BEFORE JOURNAL,
     NO AFTER JOURNAL,
     CHECKSUM = DEFAULT,
     DEFAULT MERGEBLOCKRATIO
     (
      a DATE FORMAT 'YY/MM/DD' NOT NULL,
      b INTEGER NOT NULL,
      c VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC,
      d DATE FORMAT 'YY/MM/DD' NOT NULL,
      e FLOAT,
      f FLOAT,
      g FLOAT,
      h VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC,
      i VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC,
      j VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC,
      k VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC,
      l VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC,
      m VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC,
      n VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC,
      o VARCHAR(10) CHARACTER SET LATIN NOT CASESPECIFIC,
      p VARCHAR(30) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
      q INTEGER NOT NULL,
      r INTEGER NOT NULL,
      s INTEGER NOT NULL,
      t SMALLINT DEFAULT 0 , 
PRIMARY KEY ( a , b ))
;