It seems Mavericks only perform better than the previous OSX when the Machine has SSD and lots of RAM. My old Mac Pro running 24/7, the usage of RAM usually stabilised at about 24G (with 2 profiles running at the same time and about 10 softwares opened).
Furthermore, my observation is that the OS itself use about 8G of RAM to run in full speed, anything less than that will cause the system run slower. So, if you only have 4G of RAM, the system can run, but just in a much lower speed since a lot of HDD read / write required.
Mavericks is very aggressive on fully utilise the system resources. And it only works if there is enough resource for it to use. Lack of hardware support will make this OS perform much worse than Mountain Lion or Snow Leopard.
I don't think Apple will intentionally make your system run slower, but they will intentionally fully utilise the SSD in the new Mac and disregard if your old Mac has SSD or not.
Furthermore, my observation is that the OS itself use about 8G of RAM to run in full speed, anything less than that will cause the system run slower. So, if you only have 4G of RAM, the system can run, but just in a much lower speed since a lot of HDD read / write required.
Mavericks is very aggressive on fully utilise the system resources. And it only works if there is enough resource for it to use. Lack of hardware support will make this OS perform much worse than Mountain Lion or Snow Leopard.
I don't think Apple will intentionally make your system run slower, but they will intentionally fully utilise the SSD in the new Mac and disregard if your old Mac has SSD or not.