The problem is that people use these spacemakers to provide the time they need to think about what they’re saying, and if you force them to abandon the spaces they won’t have time to fully organize their thoughts. A lot of people do something similar by shifting their eyes up, down or sideways – shutting down extraneous inputs to improve focus – which is OK in person but looks terrible on TV.
Some speakers use the Francophone trick of simply extending their words to cover the gaps. So instead of “I think that, um, you should try something new,” they say “I think thaaaaat yooouuuu should try something new.” That’s the best solution, but if it’s overused it makes speech sound unnatural. (A high-ranking Merrill Lynch exec – now retired – abused this trick to the point that he sounded like he was drunk, which is bad.)
The best solution is to think faster. I’ve found that fish oil and vitamin B-12 are dietary supplements that help me do that, and I’ve mostly eliminated dairy (casein) and gluten from my diet, too. (People should get screened for food allergies.) Sleep is also really important. Other people report good results from taking kava kava an hour or two before a speaking engagement, to reduce anxiety and help focus the mind.
Also remember that as we get older, the problem gets worse because it takes longer to sort through larger amounts of information to find the tidbit we’re looking for.