wow, you should be in Formula 1... the usual is 3-4 days, though it can vary quite a bit, but 3-4 hours sounds remarkable. But like tonyted says, how can you be sure that what exits at dinner time is actually today's lunch?
My hubby has the same problem and was diagnosed with 'Rapid Transit', he was given some powder to take but never did. If you've always been like it, I wouldn't worry too much.
Do you go normally? Do you have any other symptoms?
I have a pretty quick transit but have other problems as well and currently seeing a gastro and undergoing tests.
It took a long time and a lot of pain and suffering gastro wise to get that far though.
I've just had some malabsorbtion tests done where I had to swallow a radioactive thing and have some scans done then more scans a week later to see how fast it absorbed/stayed in my system. Results are apparantly back but got to wait for an appointment to get them and before that am going for a scan where I swallow a pill with a camera in it and they track it over 8 hours.
For me it's more problematic as it's not just going so much and so quickly after but the pain and type (without going into gross detail) and associated problems (I have a fissue which won't heal due to the chronic diarrhoea) etc...