It depends on what direction you are making landfall from, but in many cases it is not much slower. You don't have to head
due North or South until on the given latitude and then make a 90 degree turn East or West.
In practice you guess how far off your longitude could be, what your uncertainty is, and then make sure that you are on the correct latitude before your longitude could be right. A little dog leg is usually all you need.
With passages that are mostly East or West it does not add many miles. And in the South Pacific
, at least, with East-ish tradewinds and old sailing ships that could not go to weather
at all, it was better to make landfall from the East, anyways.