MySQL Configuration Changes to boost Magento Performance
innodb_buffer_pool_size 50% of available RAM
innodb_thread_concurrency = 2 * [numberofCPUs] + 2
innodb_flush_log_at_trx_commit = 2
thread_concurrency = [number of CPUs] * 3
thread_cache_size = 32
table_cache = 1024
query_cache_size = 64M
query_cache_limit = 2M
join_buffer_size = 8M
tmp_table_size = 256M
key_buffer = 32M
innodb_autoextend_increment=512
max_allowed_packet = 16M
max_heap_table_size = 256M
read_buffer_size = 2M
read_rnd_buffer_size = 16M
bulk_insert_buffer_size = 64M
myisam_sort_buffer_size = 128M
myisam_max_sort_file_size = 10G
myisam_max_extra_sort_file_size = 10G
myisam_repair_threads = 1
As seen on: http://www.mgt-commerce.com/blog/magento-on-steroids-best-practice-for-highest-performance/