What do you think of my.cnf?

[carteldabs]

Greetings, I am using the settings in the my cnf file below, but the CPU is running at around 50%. Where might I be going wrong, and what changes are necessary? Thank you.

[mysqld]
performance_schema=off
skip-networking
skip-name-resolve
innodb_file_per_table=1
tmpdir=/tmp
max_connections=500
max_user_connections=500
key_buffer_size=1332M
myisam_sort_buffer_size=192M
join_buffer_size=1M
read_buffer_size=8M
sort_buffer_size=128K
table_open_cache=3072
thread_cache_size=32
slow_query_log=1
slow_query_log_file=/var/log/mysql/mysql-slow.log
table_definition_cache=4K
open_files_limit=1024
wait_timeout=60
connect_timeout=60
tmp_table_size=2000M
max_heap_table_size=24M
max_allowed_packet=1000M
query_cache_limit=1M
query_cache_size=16K
query_cache_type=0
interactive_timeout=60
max_connect_errors=100
local-infile=0
general_log = on
general_log_file=/var/log/mysql/mysql.log
innodb_buffer_pool_size=15G
innodb_buffer_pool_instances = 16
innodb_additional_mem_pool_size=96M
innodb_thread_concurrency=8
innodb_log_file_size=512M
innodb_log_files_in_group=2
innodb_log_buffer_size=10M
innodb_flush_method=O_DIRECT
low_priority_updates=1
concurrent_insert=ALWAYS
long_query_time = 4
default-storage-engine=MyISAM

[isamchk]
key_buffer=512M
sort_buffer_size=2M
read_buffer=8M
write_buffer=8M

[myisamchk]
tmpdir=/temp
key_buffer = 512M
sort_buffer_size = 64M
read_buffer = 8M
write_buffer = 8M

[mysqlhotcopy]
interactive-timeout