There's probably nothing more frustrating than to have a successful interview with a company and then experience delays in receiving feedback from the recruiter. Sometime it just seems like the process is going nowhere fast. Why does this happen? Peter Weddle at CareerCenterToolbox.com illuminates the issue in his article How Recruiters Work and Why.
The big take away from this is that the delays usually are not personal but have more to do with how the recruiting function works within companies. So, don't allow yourself to become frustrated. Simply understand that candidate follow-up is both needed and expected.