Federers forehand development

This is something I have thought for a while, and forgive me if this has already been discussed but I have been watching back a lot of old Federer matches and I cannot believe how different his forehand is. It looks like he adds more spin than he used to, its not quite as monstrous but slightly more delicate. Could this be a re-adjustemnt as he has to rally more than he used to?

https://www.youtube.com/watch?v=9Rj3QoKt764 Wimbledon 2006 his forehand is absolutely massive

https://www.youtube.com/watch?v=MqExjxCJr4Q Wimbledon 2012 still a great hot but seems to be hit with more safety


https://www.youtube.com/watch?v=B-TZeGkEQWc US Open 2005 dominates all points

https://www.youtube.com/watch?v=KAxK9B4wUSg US Open 2012 still a great shot but more of a rallying shot


Is this a combination of age and slower courts or has he just decided he wants to stay in the point longer to compete against baseliners such as Rafa, Andy and Novak?

Not convinced whether there is such a huge change or not.

I think the clips illustrate how the surfaces have slowed in this time period, in my opinion. He is just reacting to that I think.