If you have one large app and you split it into two, but you have cross up relationships then you'll have gained nothing. Cross up relationships are not the problem. Really the problem is when you have an app or a cluster of apps which are cross linked to each other then you are restricting that app to run on one server process. If you have a busy app with lots of concurrent users than performance will be degraded and your users will complain.
The best practice would be to have more apps and not have them cross linked. The only way to do that if you have common tables is to use Sync tables or some kind of pipeline to mirror the information across. That way each app gets their own server process.
------------------------------
Mark Shnier (YQC)
[email protected]------------------------------