Why would you want to appear better then you are at the interview? You'll get found out eventually later, and this will end up just spending your time.
There are plenty of developers/programmers who do not ace tests with rigid constraints, but are quite competent in a more relaxed setting.
That is they are not the 1% that the all hirers, but they are maybe top 20% and that is actually what most jobs require no matter the delusions of hiring managers.
Granted this particular job might be an exception but I doubt it.
