I am aware that we got the feature back that allows to build stuff w/o the techs at a much slower speed.Read the tech very carefully. For example, you may notice on exploration there is a line that says, "Build roads 75% faster". Other techs such as mining, etc. have the same type of thing for a subsequent improvement.
...it's just that even after researching the right techs they still need XX turns ...
So I got the corresponding techs which should allow normal building times.
But my workers are building improvements at improved/normal building speed just on non-forrested terrain, not in forests/Ancient forests.
E.g.:
Building times for a Workshop for a freshly built worker (80% workrate)
Non-forest-Tile 8 turns
Forest tile 19 turns
Ancient Forest tile 22 turns
Cottage:
Non-forst tile: 5 turns
Forest tile 14 turns
AF: 33 turns