Perhaps because of the way that the underlying memory works. If Yamaha has all 8 libraries stored on a flash part - and execute a "Flash erase" to the entire part - they may have to first "cache" (shadow) all 7 libraries to some other temporary memory area before doing the erase, then erase, then restore the other 7 libraries from temporary cache back to the flash. Ignore, for the moment, if you are using any more than 1 library. I actually do not know the underlying architecture - but am offering some insight on general principles which would answer your question more than a specific laser-focused answer that could be provided by Yamaha engineering.

Although data can be changed on a part which Yamaha designates as "Read Only" - what they really mean is that the part cannot be arbitrarily written to at any location like more volatile memory. Of course, since you can change the contents - it is not "Read Only" in a strict sense.

It would be clear if the architecture (memory parts and type) were laid out in a block diagram and you had some background to understand the designations. The architecture could be annotated to demonstrate some key features like max # of write cycles, data retention time, memory cost, etc - which would help demonstrate some of the "why" the architecture was chosen.

But the general rundown would be that the Library section is slower memory to update/modify than the user section. It's (Library memory) less expensive - so there's more of it. The purpose of the Library section (since it is limited in how "fast" it is to update) is to commit changes you can make quickly in the user memory section. And these changes committed to the Library are meant to be long-term. Meaning you're done editing parameters, sorting through performances you want to delete, etc - and want to "forever" hold performances - so you file them in the Library. Just like at the library, it's a hassle to bring books home. You have to have your library card, check out the books, get fined if you're late bringing them back, etc. So you better have a clear plan of usage for the library. This is verses the user section where you can willy-nilly use the books (performances) and make changes / etc - since the user section does not require the same "check out" process.

This "check out" process I'm going to say is this extra time you notice when deleting any library regardless of the size.

The Yamaha approach to memory management and part selection is part of what allows the boot time to be faster than some other keyboards while still retaining a reasonable size of user configurable space.

Ok cool. Thank you Jason for your reply.

I love the Montage so so much. It is a joy to create with. But the joy gets interrupted by the Library management system's load and deletion times. This is only a hindrance to my creative flow because I am constantly building new patches and transferring/loading/deleting newly made Waveform/Library files from John Melas' Waveform Editor to experiment with on the Montage.

"Load all your files at once! Do it all in one hit and go make a cup of tea! Work with the limitations, don't fight against them!" I imagine Bad Mister saying.. :p

Hello Joe - I have similar problems in that I use Libraries to separate different projects, so must keep loading/deleting them so as not to exceed the miserable 8 limit imposed by Montage. I notice that they delete off the Montage in a few seconds, but the same Library takes tea-making time off the USB back-up. Jason's probably nailed that. As often as not though, it helps by making me stop and think - I tend to go off Bang! and get things wrong in the process, so an enforced pause is often good. Same applies to loading. BM and Confucius speak the same tongue ...