how to improve performance in libpq?

Hi,All,

     I have a question in libpq.the postgresql dadabase about 32MB(base on backup),and I tried to analyze query as :EXPLAIN ANALYZE SELECT .........where id=123 ,got the total actual time is 2.882ms.

     Now,I start a test programe base on ../src/test/examples/testlibpq.c ,which has 900 connection pools,and the id will be to increase for each query.In total I test 160000 queries, used time 1012s. That seems a greate different with 2.88ms/each query.    any idea?

     test environment      :

     database hardware    CUP  2*Xeon 5405

                                    MEMORY  DDR2 16GB/800 with DIMM

                                    HARDISK   160GB/8M SATA

      network :LAN 1Gbps 

     

 

      configuration files:

         max_connections = 3000

         shared_buffers = 64MB  

         work_mem = 4MB                      

         maintenance_work_mem = 4MB            
         max_stack_depth = 1MB                  
         the others as default.

       

        any idea?

        I hope you can understand,thanks.