Callgrind is certainly dispensable; just use a profiler. They are much, much faster, and more accurate as well. (Callgrind is using an idealized model of CPUs as they were around 1995, which doesn't match up all that well with how they work today.)
There are some situations where I find myself using Callgrind, in particular in situations where stack traces are hard to extract using a regular profiler. But overall, it's a tool that I find vastly overused.
There are some situations where I find myself using Callgrind, in particular in situations where stack traces are hard to extract using a regular profiler. But overall, it's a tool that I find vastly overused.