speed on Postgresql compared to Mysql

Hi,

Talking about insert, I know Mysql is fast than Postgresql.

I've made the following test :

40'000 insert (accouting context) using Perl and dbd :

Postgresql :
text : 4 min 53 s
varchar : 4 min 49 s
char : 4 min 49 s

Mysql :
text : 0 min 29 s
varchar : 0 min 29 s
char : 0 min 29 s

So we can see Mysql is about 10 times fast.

Also we used Postgresql for Radius (authentication) et we have to make 3
vacuum per day otherwise the first server is overload and the user go to the
backup server.

Is it normal or my Postgresql is not well configured ?

Thanks in advance.