@Agni if you look at this series as a slice-of-life series at heart, there is development. though it might be too subtle for your liking. i mean, that's what slice-of-life things tend to do; fleshing out the picture to the boring detail to emulate daily life ambience in its slow pace. correlation inbetween chapter was not a priority in this type of story presentation as every event that happened in this manga is not objectively-driven, but more caused by purely chance meeting. and in the last 40 chapter was not all filler. we get new characters as well. which is the point of this manga. exploring random characterized stereotypes and how komi handle her communications with them.
as far as it goes, it do feel slow paced but this manga still didn't abandon it's introduced premise like nisekoi (edit: to prolong the story meaningless-ly until he felt like ending it). another reason it might felt slow was probably the weekly release of this manga. it probably wouldn't felt as slow if one read this back after the manga is completed.