Yes, but their taxes will also be used for infrastructure and social services to support them in Canada, per the government's annual budget, as there will now be more people in Canada. It's not like the immigrants' taxes can be channeled to processing immigration only.
The process has been streamlined a LOT in the past few years. I sponsored a partner from the US (inland, mind you, but with a 'straight forward' application) a few years ago and it took 13 months to get to the AIP stage, and then several more for a final decision and landing. This time we got AIP in exactly 6 months.
When I was a child, it took my family 4 years to immigrate to Canada.
If they suddenly started processing applications in 1-3 months, there would still be someone here complaining that their application wasn't processed yesterday.
Keep in mind that this process involves several organizations and processes that all have a ton of paperwork/data entry/etc. and actually takes real people real time to complete.