About the External Cache

sir,
When the biginning of Pentium series we can see upto 512mb cache on Mother Boards.when P III arrived it will come down to 256 and noe 128.what is this shows? When we disable the external cache of P I system the perfomaance result as dead slow onthe otherhand the P III sysems are not… kindly try to reply me
jayadev, India ,Kerala