I don't know the machine that you have ...
Are you meaning the hesitation is when you are starting to sew? or the whole time you are sewing?
I understand there are some machines that have a gradual start. By this I mean that when you start to sew, it doesn't pick up speed immediately, slow, then a little faster then to full speed! Kind of like a race car being kept a little slower til it's down the track a bit.