[linguae]

The interesting thing about this is that early Mac OS X was the opposite, with each release being faster than the previous. The very first consumer release of Mac OS X (10.0, Cheetah, 2001) was said to be rather sluggish. Addressing this, Puma was an improvement over Cheetah, which was then replaced with the even faster Jaguar, which was replaced with the even faster Panther, which was finally replaced with the even faster Tiger. There were some slowdowns when Leopard was introduced (which is why I have Tiger installed on my PowerPC Macs), but this was fixed when Snow Leopard was introduced, which had no new consumer-facing features but had many optimizations and infrastructural improvements.