I get the same result with that patch. With increasing the polyphony and having many parameters, the preset loader blocks for some time, which seems to be the cause. When using the global mode, the parameters are saved for each voice (which is a bit redundant...), but on loading them back it's tricky to make something reasonable and robust to apply them to more than the first voice.
Anyway, I spent quite some time to see what could be done about the situation you're experiencing. In the end I made it so that the loading and saving is performed in a separate thread. Thus the audio thread is no longer blocked on save and load (@jaffasplaffa: that should automatically get rifd of the BLIP, BTW) . That stops the timeout you're seeing from occurring.
While a threaded preset manager is nice to have, it doesn't solve the poly problem. What I found is that using the SubPatchV1 mode seems to cover poly patches, with the drawback of being sensitive to alterations in the patch. Some simple changes to the firmware and/or patch code generator could fix all of that, but I don't think that's going to happen, so at least for now this is as good as it gets.
Please try out the threaded preset manager, and let me know how that goes (sync the libraries to make it available):