其实这是 mysql 配置上的问题， 默认的 linux 中， mysql 的配置是 my-large.cnf 配置，该配置适合大型服务器。有高内存，比如2G，4G内存的，适合使用，而一般512M内存 的就不行了。它会占用512M内存来保存系统 mysql 的进程，这些进程长期堆质，并不释放，导致系统缓慢。所以，把配置改变成为 my-small.cnf ，小型配置就可以了。它的配置如下：
    # Example mysql config file for small systems.
    #
    # This is for a system with little memory (<= 64M) where MySQL is only used
    # from time to time and it’s important that the mysqld deamon
    # doesn’t use much resources.
    #
    # You can copy this file to
    # /etc/my.cnf to set global options,
    # mysql-data-dir/my.cnf to set server-specific options (in this
    # installation this directory is /var/lib/mysql) or
    # ~/.my.cnf to set user-specific options.
    #
    # One can in this file use all long options that the program supports.
    # If you want to know which options a program support, run the program
    # with –help option.
    # The following options will be passed to all MySQL clients
    [client]
    #password = 你的密码
    port = 3306
    socket = /tmp/mysql.sock
    # Here follows entries for some specific programs
    # The MySQL server
    [mysqld]
    port = 3306
    socket = /tmp/mysql.sock
    skip-locking
    set-variable = key_buffer=16K
    set-variable = max_allowed_packet=1M
    set-variable = thread_stack=64K
    set-variable = table_cache=4
    set-variable = sort_buffer=64K
    set-variable = net_buffer_length=2K
    server-id = 1
    # Uncomment the following if you want to log updates
    #log-bin
    # Uncomment the following if you are NOT using BDB tables
    #skip-bdb
    # Uncomment the following if you are using InnoDB tables
    #innodb_data_home_dir = /var/lib/mysql/
    #innodb_data_file_path = ibdata1:10M:autoextend
    #innodb_log_group_home_dir = /var/lib/mysql/
    #innodb_log_arch_dir = /var/lib/mysql/
    # You can set .._buffer_pool_size up to 50 – 80 %
    # of RAM but beware of setting memory usage too high
    #set-variable = innodb_buffer_pool_size=16M
    #set-variable = innodb_additional_mem_pool_size=2M
    # Set .._log_file_size to 25 % of buffer pool size
    #set-variable = innodb_log_file_size=5M
    #set-variable = innodb_log_buffer_size=8M
    #innodb_flush_log_at_trx_commit=1
    #set-variable = innodb_lock_wait_timeout=50
    [mysqldump]
    quick
    set-variable = max_allowed_packet=16M
    [mysql]
    no-auto-rehash
    # Remove the next comment character if you are not familiar with SQL
    #safe-updates
    [isamchk]
    set-variable = key_buffer=8M
    set-variable = sort_buffer=8M
    [myisamchk]
    set-variable = key_buffer=8M
    set-variable = sort_buffer=8M
    [mysqlhotcopy]
    interactive-timeout
    以上配置足够 你的系统高速运行 mysql 了，sleep的进程，很快就被回收，不占资源，这非常适合小型服务器。一般个人托管的服务器也很适合。