mysql closing tables taking double the time of process
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i have delete query is taking long time. when i check in `processlist` status is showing `closing table`.

it is taking long time close tables.

ex: i run a query total time is : 1:42 Sec. in that 80-90 sec are for closing table.

This is happening for all queries like `load data` , `select` and `insert` 

below is my.cnf settings

    key_buffer_size = 2G
    sort_buffer_size = 8M
    read_buffer_size = 10M
    read_rnd_buffer_size = 10M
    join_buffer_size = 2M
    bulk_insert_buffer_size = 100M
    myisam_sort_buffer_size = 64M
    
    #tmp_table_size = 100M
    #max_heap_table_size = 64M
    #max_allowed_packet = 64M
    
    table_cache=1024

my meminfo

    [root@localhost ~]# free -m
                 total       used       free     shared    buffers     cached
    Mem:          7862       6686       1175          0         11       4091
    -/+ buffers/cache:       2583       5278
    Swap:        15998         18      15980


please tell me what kind of changes need to do in cnf.

Thanks..