flx2015 said:
and it's only in the past few years that things started to slow down. That doesn't make sense to me...
Why wouldn't this make sense?
As time goes on, the country gets more populated, so more restrictions would need to be in place to limit the flow of immigrants. Also, as various events happen around the world, bigger security measures come into play. Thus making the review process more arduous.
Another reason that SuelDansMonBocal mentioned is that some Visa Offices has closed. For example, there used to be one in Berlin, Germany, but that closed down and everyone in Germany now need to have their stuff reviewed in the Vienna office.