Here is some information I found on CIC site: http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=1185&top=3
Why did processing times information change?
Prior to December 31, 2015, processing times for many of our services were displayed by visa office. This was useful when applications for permanent or temporary residence were always processed by the nearest visa office. However, we now have the ability to move applications around our global network to ensure they are processed as efficiently as possible. This means your application may not be processed at the office closest to where you live.
For many services, instead of asking about your nearest visa office, you are now asked for your country of residence. This provides you with a more accurate processing time. For other services, you may see a single processing time, no matter where you live. This is our commitment to process applications within that time. These processing times are updated on a weekly basis.
In addition, we redesigned the layout to be mobile friendly so that you can get the information you need anytime, on any device.
Processing times will vary based on:
Type of application submitted;
Volume of applications received;
How easily we can verify information;
How well and how quickly you respond to any requests or concerns;
Whether the application is complete.
Many more people want to immigrate to Canada than the Government of Canada can bring in each year under our annual immigration plan. Applications received after the maximum has been met may have to wait longer to be processed.