How to profile compile times of a source code?

[Ahmet Sait]

I'm looking for ways to figure out what parts of the code slows 
down the compiler other than brute force trial.

Can I use -vtemplates switch for this?
Would -v (verbose) switch helpful in some way?
How would I know if my bottleneck is ctfe or templates?
How do the compiler devs approach this issue?

I'm interested in all kinds of tricks to the point of debugging 
the compiler itself although anything less complicated would be 
appreciated.