We have a Windows 2003 Enterprise Edition server (64bit) running only MySQL 5.1.45 64-bit. It has 16G RAM and 10T of hard-drive space in RAID 10. We are having horrible performance from mysqld (85-100% CPU utilization). We were running a smaller machine with better performance, so I am assuming our my.ini file is not correct for our current machine. The my.ini file is as follows:

[client]
port=3306

[mysql]
default-character-set=latin1

[mysqld]
port=3306
basedir="D:/MySQL/"
datadir="D:/MySQL/data"

default-character-set=latin1
default-storage-engine=MYISAM
sql-mode=""

skip-innodb
skip-locking

max_allowed_packet = 1M
max_connections=800
myisam_max_sort_file_size=5G
myisam_sort_buffer_size=500M

table_open_cache = 512
table_cache=8000
tmp_table_size=30M

query_cache_size=50M
thread_cache_size=128
key_buffer_size=3072M
read_buffer_size=2M
read_rnd_buffer_size=16M
sort_buffer_size=2M

#replication settings (this is the master)
log-bin=log
server-id = 1

Does anyone see anything wrong with this setup? For a machine with this much RAM, why in the world would mysqld eat up so much CPU? I know we can optimize some queries, etc., but it did run okay on a smaller machine, so I am pretty sure it is the config.

Thanks in advance for any help.