Just checked R2015b an this significant problem remains.
For me and my research, you guys have broken one of the best parts about Matlab, quality vectorized figures. What is the point of having vectorized graphics if you are just going to chop up polygons into a large number of tessellated triangles?
I use contourf regularly to produce publication quality figures and the new graphics engine has made Matlab completely unusable for this purpose. Thus, this 'upgrade' represents a large step backwards for me.
My suggestion to anyone who needs a 'workaround' is to downgrade to Matlab R2014a until they fix this issue.
Here is a simple illustration of the problem:
I have attached the results from R2014a, R2015b and R2015b using the 'opengl' print option.
The individual pdf files sizes are, R2014a : 23 KB, R2015b : 245 KB, R2015b openGL : 77 KB
The R2015b version is an order of magnitude larger in file size due to the tessellation and looks terrible. The R2015b openGL version is better but is a raster image which defeats the utility of vectorized graphics. Only the R2014a result is usable.