Query performance

[Maurizio Mariani]

Hi all,
I've some problem with dedicated server performance querying my database.
I've charged wordnet database on my dedicated server.
When I querying using 2 or more join mi processor go in overuse of resources.
I can't understand why if I query mi machine with 2 processor and 4G ram i obtain good performance, but on whene i queryin on my dedicated server (8 processor and 8G ram) the cpu usage value indicate an overuse of resources, this is my.cnf file

[client]
port = 14810
socket = ***************
database = **********
user = *********
password = ********
default-character-set = utf8

[mysqld]
port = 14810
socket = **************
tmpdir = **************
datadir = **************

key_buffer = 2G
max_allowed_packet = 16M
thread_stack = 192K
thread_cache_size = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
max_connections = 100
table_cache = 64
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit = 1G
query_cache_size = 2G


# The maximum size of one packet or any generated or intermediate string, or any parameter sent by the
# mysql_stmt_send_long_data() C API function.
[mysqld]
max_allowed_packet = 500M


Any suggest would be appreciated
Tx a lot