Think of it this way. If you put a flavoured ice block in your mouth, it will stay there for a while and eventually melt. You'll enjoy the flavour for longer, but you won't get all the flavour at once. But if you were to crush up that ice block and then put it in your mouth it would disolve very quickly and you'd get a quick burst of flavour. However it would be gone quite quickly too.
It's the same with crushing up pills as opposed to just eating them whole. By crushing it up you're allowing it to be absorbed into your system faster, which will mean you'll get effects faster and thus it will probably be more intense. But the trade off is that it won't last as long because you'll use up all the drug quicker.
