Why the huge difference between etch and lenny MySQL

Question

I've been working on a program for the last year. The development environment is working with a database in MySQL running on debian etch version mysql Ver 14.12 Distrib 5.0.32, for pc-linux-gnu (i486) using readline 5.2. The production environment is working on debian lenny with version mysql Ver 14.12 Distrib 5.0.51a, for debian-linux-gnu (i486) using readline 5.2. I was just timing some database access and what takes in the development environment 150 seconds, takes 300 in the production environment. I checked the /etc/mysql/my.cnf files on both systems and the only differences are

# development 
bind-address        = 10.168.1.82
log_bin         = /var/log/mysql/mysql-bin.log

# production
bind-address        = 127.0.0.1
myisam-recover      = BACKUP
#log_bin            = /var/log/mysql/mysql-bin.log

I dump a database from the production and load it into the development and with the same server everything takes half the time !!! What should I check?