One of the big problems for the Crown is that most of their lawyers leave. A criminal law lawyer will either go into a larger firm or work for the Crown. Lawyers who are ambitious don't stay with the Crown. They hone their skills and start their own practice. After 5 years, they're gone. I've seen court appearances move because the Crown lawyer did not show up.  The Crown is short staffed , seriously short. 
An example. Here in Cornwall, for years( 70&80's) there was a Crown lawyer who had a lethal prosecution record. If you had to go up against him you were in trouble. He was so good that by the late 80's he went on his own and is now the top criminal lawyer in Eastern Ontario. The good one's don't stay with the Crown. Therein is a big part of the problem with regards to delays.