fastest way to write spark dataframe to phoenix table

I have a wide phoenix table with > 159 cols and around 60mil recs which I am accessing through spark and reading into spark dataframe and then performing many analytical functions. In the end however when i try to write this processed dataframe with only 7 mils recs to another table in Phoenix using "df.write" but its very slow. It takes 58 mins to write this data. My question is, is there a better way to write data from spark dataframe to phoenix table? Please suggest.