Your performance with remote databases depends on a couple of things:
1. bandwidth between servers
2. How and where you process data. For example, if you have a package on the local instance that pulls data from the remote instance and does a calculation on the local instance, the performance will be slow. The less that has to be pulled over the link the better.
3. I have heard about some performance problems with two-phase commits, although I have not verified these performance problems.