MATCH AGAINST become slow using *

[Luca Libonati]

Hi all,
I'm really not able to sort out this issue.

I have this query that run fast (about 1 second) on a database of 6 million of records:
SELECT *, MATCH(name,surname,alternatenames) AGAINST('+napo*' IN BOOLEAN MODE) FROM names WHERE MATCH(name,surname,alternatenames) AGAINST ('+napo*' IN BOOLEAN MODE) and (class='P' OR code='m' OR code='PC' OR code='PCL') order by population DESC LIMIT 0,10

if i change the query in this way it runs really slowly (117 sec):
SELECT *, MATCH(name,surname,alternatenames) AGAINST('+don +chi*' IN BOOLEAN MODE) FROM names WHERE MATCH(name,surname,alternatenames) AGAINST ('+don +chi*' IN BOOLEAN MODE) and (class='P' OR code='m' OR code='PC' OR code='PCL') order by population DESC LIMIT 0,10

What i expect from this query is to search for people in fields name,surname,alternatenames where the name start with "don chi" and must contain both words.

Could someone help me to sort out this issue?
thanks a lot