I have 761,592 obs for 31 variables on users behaviours towards online ads. Out of 31 variables, 28 are categorical. Many cat. variables have more than 10 categories. I am using Amelia for missing data imputation.

It's taking very long time. Are there other ways to do it fast? What's the Amelia limits on number of observations ?

Is there any R-package which perform better on large dataset for missing data imputation?

I checked for complete cases, there are only 172 complete cases which is very insignificant as compare to total dataset.