1998 Honda Accord speed

I want aske why the honda accord 1998 it has CPU amircan System when its start from 0 its very heavey than when the speedo meter gage cross 40 KM its gone fast as normal, olso is there any solustion, becouse some one tell me the proble is in computer program, he tell me to chinge it to other modle with a semaler seral number, than I chage it but I have the same problem.
please can you solve this problem.