I have an anecdote about daily stand-up meetings. The project I was on had its tasks written up in Excel spreadsheets, planned up to 2 years in advance. The management discovered, after seven years, that things were not being done that should be done.
So they implemented daily stand-up meetings at exactly 8:50 am, including every single person on the development team, as well as all the testers. The natural politicians on the team immediately pivoted towards writing down every bullshit thing they did during the day, so they could recite them the next morning as evidence of productivity. Incidence of scheduled meetings that would require at least one of the seniors to be present exploded.
Every single one of those damned meetings was scheduled for 10 minutes, and lasted at least 30.
The stand-up is not the problem. Incompetent management is the problem. Management fads won't do anything to address the underlying deficiencies. The actual problem with that office is that smart and unethical developers are leading the incompetent managers around by the nose, using the very process and metrics that the managers had created to hide their lack of development knowledge.
As a result, the senior developers assigned themselves the privileged tasks that sound important but don't actually require much work, assigned the grunt labor to juniors, and gamed every last one of the management metrics to make sure everyone on board with "the program" gets paid until the gravy train runs off the cliff.
So naturally, every last line of that code base is DailyWTF candidate material. The management does not understand technical debt, so the seniors issued them high-interest loans from their own bank.
This is not the fault of the developers. It is 100% the fault of the managers that allowed that toxic creature to take root.
So with respect to the question post, I suggest that the "slow" employees may actually be testing their new manager's capability to manage them. This is particularly relevant if any of them have ever worked for another company.
Assume they are trying to establish their own slack margin, so that they can safely read HN every morning, or some other equivalent time-waster, without falling behind on assigned tasks. If so, implementing a daily stand-up will only confirm that you are a management novice that can be manipulated.
Just establish a tough, but fair, work standard, and check to see if the "slow" guys speed up in response, or continue to struggle for more hours. For the former, you will need to court their favor by assuring them that good productivity will not be punished. For the latter, you will need to continue their education by sharing the knowledge and experience you and the faster developers have acquired during your careers--but subtly, so as to not embarrass them before their peers.