Slowing Down?

While CodeIgniter is executing....
Is there a way to know.
Which part of the codes of CodeIgniter is the cause of slowing down while executing?

If your answer is yes, then share it.
If your answer is no, then perhaps the next release version 4 I hope it must have this feature.

The reason is I ask this question, Is because I always blaming the hosting company because the site is slowing down.
But when I tested it on my localhost the app that I'm developing is the culprit.

Your thoughts?

Thanks in advance.