Hi Sivanantham,
There are faster delta-sigma ADC's but, faster data rates usually come with higher noise. Right now the ADS1255/6 and ADS1259 are our lowest noise delta-sigma ADC's. The ADS1259 has lower noise at faster data rates, but it does not have an integrated PGA, which would need to be added and could contribute to the noise.
Are you using a ratiometric configuration?
Another technique I've seen with weigh-scales is to first sample the input at a fast data rate to get data out right away, and then slow down the data rate to for more accurate measurements.
Yet another option (though not the most economical), is to use 4x ADS1255's in parallel and at a lower data rate for the required data rate and lower noise performance.
Regards,
Chris