Use blockFactor to increase query performance Adding blockFactor to a query can significantly improve performance. To add blockFactor, examine the data that is being returned. Determine the maximum size (in bytes) of each row. Take that size and determine how many times that number would divide into 32k. That number is your blockFactor, but be aware that the max blockFactor is 100. So, if for example you were getting 200 bytes per row, you could easily fit over 100 rows into the 32k buffer that CF 'grabs' at one time. If you know at runtime that you will have less then 100 rows returned, for example you're writing a query that either returns 0 or 1 rows, do not bother adding the blockFactor attribute.