I think a lot depends on your location.
In South East Asia, 2 to 3 months is the norm for any management position and the bigger the company is, the longer the notice period becomes because you are normally overseeing more people and projects.
Not too sure what you mean by "Development Manager" but if it's Software Development in a mid sized company then 3 months is pretty common in my part of the world.
Since it's pretty much the norm here for management positions, it doesn't really deter future employers unless its for an urgent need. Even in those cases, there's almost always an option of paying off the current company in lieu of serving the time so if they really want you that badly, they can pay for it.
From my experience, you don't normally have to serve out the full length as long as you can convince them that the handover process can be completed sooner and that you have a capable replacement. If you think your current company might be flexible in that regard, just tell prospective employers that it's "3 months negotiable" and go from there.