I would say that they are indeed glacially slow, but so much entered the pipeline in a short period that we are finally seeing some larger-scale results these last few years. The only area that seems to go extremely quick is the Seaport, depending on the project. As much as we have had going on lately it also remains true that we have only topped off 4 buildings over 500' in more than 15 years. I think the big difference is that we were stuck with only 2 over 200 meters for a 40 year stretch, and suddenly we're up to 4, with a 5th out of the ground, and South Station Tower promising to be a 6th. Visually, this is a very transformative stretch because of those projects.
However, we still seem to have an issue in the 300'+ category. Right now we only have 2 projects over 300' out of the ground and growing, but like 8-10 over 200'. I closely follow the stats on projects out of the ground and growing, and it is typical that we never have more than 2-3 simultaneously over 300', and often less than that. The best stretch lately has been 1 Dalton, Hub residential, and Wynn casino all growing at once.
By the way, no development illustrates the glacial pace of this city better than the South Station Tower. I have been waiting since seeing renders for a "new tallest" in Boston Globe, back in the mid 1990's! There have been proposals since well before then as well! So if you want to argue that development is NOT slow here, this is the wrong thread to do it!