The formulation of water-based pigment inkjet inks constitutes a major challenge: in addition to be perfectly stable colloidal suspensions, water-based pigment inks should strictly meet all the requirements imposed by the printhead specifications regarding flow properties, surface tension and density. The nature and the quantity of dispersing agent used to stabilize the pigment particles in suspension are crucial issues that can significantly impact the ejection phase. Inkjet inks must be stable over time and during jetting whatever the ejection duration and cycle imposed by the digital printing flow. Each nozzle can be activated according to different ejection cycles. All the nozzles are not jetting at the same time. Some idle nozzles do not jet for a certain duration which can lead to ejection disturbances when they are restarted after this period. The latency refers to this negative behaviour after periods of sitting idle in the printhead. So far, solutions for minimizing the impact of latency have been proposed by adjusting the formulation but no scientific research tried to understand precisely the causes behind this phenomenon. This paper tries to show the significant influence of the dispersing agent on the latency issue for the jetting of water-based and pigmented inks.