I also like to share my experience with FB 2.5 on Win 64.

I took a different path to optimazed FB performance.

From the very beginning I have choosed SC architecture for its multiple thread capability.

And these are the main setting in my db
- Page Buffers = 1024
- DefaultDbCachePages = 0

I set these parameters to its min value because Firebird database is placed on a RAM disk.
I predict my database size won't exceed 64GB and also I can upgrade CPU RAM up to 128GB.

With those setting, you have SC architecture with share cached like in SS.

CPU has a UPS and backup runs 3x times a days. It has been runs about 3 years without serious problems.

I don't know how its speed compared to database on a disk, but it is very fast.

Just for raw info, on SSD(sata 2), random read 4K +/- 18 MB/s, random write 4K +/- 52 MB/s.
On RAM, random read 4K +/- 1061 MB/s, random write 4K +/- 770 MB/s.