ADF5610 - PN where there is only N integer vs. N integer + N fractional

Hi During my measurments with the EVB i saw that there is a much difference between two states, i compared it with TI LMX2954 and in their IC EVB there is only tiny diff between 

syntysiezed freqs with N integer only vs. N integer + N fractional , is this conclusion true ? i mean maybe i have some ADF5610 Configurations issues? 

i use High Preformance and follow all the instruction regarding charge pump up and down gain.