In my opinion, PrusaSlicer aims for the most robust printing process at the cost of a higher demand for material in the standard configuration.
I totally agree with @0scar that the small pillars have a high tendency of falling over with increasing height of the print.
To handle the waste of material you could use the feature "Paint-On Supports" (since version 2.3) to tell the software where support material has to be used. The feature can be found on the left panel while on "3D-Editor View". This is an extra step to prepare your model, but to speed up your post-processing I think it should be worth it. Prusa improved the modifier by "you get what you click".
If you want to stay in Version 2.2, I think you have to use the generic modifiers, which are a lot more time-consuming to set up.
Paint-on supports @Prusa Knowledge Base