Hello Daniele,
I do fully understand that the effective memory limitation on Leopard with computers having 4 GB or less of physical memory is a disadvantage, and we do state that clearly in the Hauptwerk prerequisites and elsewhere, e.g.:
http://www.crumhorn-labs.com/Hauptwerk- ... mory.shtml
In practice the difference is significant but not huge since only about 3.2 GB could be used by Hauptwerk under Tiger on a Mac with 4 GB or physical memory.
On Tiger, unless the sample data were locked into physical memory ('wired'), almost all of the data would go straight to the page file causing audio glitches, even with very small sample sets, so there was no alternative but to wire them. However, the disadvantage of wiring was that OS X could become unstable and crash or behave very strangely if large amounts of physical memory were wired, and there was no reliable way to determine how much physical memory it was safe to wire before that would occur.
In most regards, Leopard's memory manager is much better in that it keeps sample data in memory without needing to wire (although up to a slightly smaller maximum amount on Macs with 4 GB or less installed than was possible by wiring under Tiger). Not wiring the memory avoids the problems of system instability, but trades that off for the risks of audio glitches if the user doesn't ensure that sample sets fit within the available memory.
The other key key issues is that attempting to wire any fairly large amount of memory on Leopard simply causes it to crash! Hence wiring is simply not possible at the moment on Leopard. That might simply be a Leopard bug, and a future Leopard patch might make it possible to wire the memory again (as with Tiger), but in the meantime we haven't found a way around that other than avoiding wiring memory completely when Hauptwerk detects that it's running on Leopard.
In summary: Tiger wouldn't work unless the memory was wired, but then risked instability if too many data were loaded. Leopard won't work with wired memory and so instability is no longer a risk, and it's improved memory manager makes it unnecessary to wire the memory, but the trade-off is that a little less memory can be used.
So it's basically a trade-off between stability and audio glitches when too much data is loaded.
If we can get Leopard to work reliably with wired memory in the future then we certainly will do that, and the effective memory limit on Macs with 4 GB or less of physical memory would then be back as it was with Tiger.
Best regards,
Martin.