We just released Foxmarks 2.0.39, a minor upgrade over 2.0.38 which fixes two bugs. We'd appreciate it if you'd download it and let us know if you see anything unexpected. This is our release candidate for AMO -- if no new problems crop up, we will likely make this available on the Mozilla Add-ons site (for a while at least) tomorrow.
Separately, we believe we have resolved nearly all of the server performance issues that have caused us all such grief. Those who have had problems with auto sync over the past few weeks should find that it now works much more reliably. Monday morning will be the next big test for us, but today was certainly the smoothest day since our launch in December; we are cautiously optimistic about the future. Thanks again to those of you who have had patience with us while we worked through these issues.