Example:

1. Open Firefox
2. Visit Configuration profiles from NVDA.
3. Create a new profile called Web and assign it to the application.

When switching between Firefox and other applications, significant delays are encountered.
This is true of any application for which a separate config profile is created, e.g. Microsoft Word.
This behaviour has been observed
in NExt and Master builds of NVDA this week. Behaviour does not occur NVDA 2017.4. Behaviour is present in NVDA 2018.1 RC1.