about performance of postgreSQL

Dear master:
I have learned postgreSQL for serveral days, now i meet some problems. when I use a TPCC(Transaction Processing Performance Council) test program to test the performance of postgreSQL , postgreSQL works very slowly, it almost need 1 minute to finish a transaction, and the CPU percent is almost 100%,
the test environment is :
OS: redhat 9.0(ext3, default configurations)
Server: postgre7.3.4(default configurations) , PIII 800M, 1G Memory
Client: tpcc test program,using ODBC API, PIII 800M, 1G Memory
when using SQLServer, it can work on a workload of 40 Warehouse,
but postgreSQL can not work even on 1 warehouse. I think there must be
some problem with my postgreSQL, can you help me?
I am in china, and my english is very poor, but i hope you can give
me some advice, thanks.

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