I worked on an application a number of years ago where it was trying to load all the comments and details about an internal bug tracker into memory. It must have worked fine at first, but after time it was a POS.
If the database fits onto client hard drive and the modifications are rare, preloading everything is almost always better.
If you have a dynamically changing system such as bug tracker, it is still possible to go fully local, but that would require considerable cooperation from server side. When the back-end does not have a fast, efficient API for sending diffs, you may get stuck waiting for it to be implemented. But that's a purely organizational problem.
Of course, all of above applies to actually saving data to permanent storage. Storing everything in memory is a sin by itself.