I felt the pain of OS X Lion slowing my Macbook Pro after upgrading from Snow Leopard. Boot time doubled for me for some reason.
I did a clean install of Mountain Lion, and ML has been a lot faster booting and snappier (lack of better term) for all programs. This is my favorite part of installing Mountain Lion.
Installation of Lion on any of my Macs did not result in slow
performance. As far as Mountain Lion, I have only installed
on my 2011, 13", 2.7 GHz Macbook Pro so far and see no performance
difference between Lion and Mountain Lion. Actually, updating from
Snow Leopard to Lion actually made it faster.
Jury is still out on my other Macs as I haven't gotten around to
Ok, I've been working on macs for years. What is a 'clean install' vs. the download from Apple?
Clean install - completely wipe and reformat hard drive and
install OS from scratch. Then reinstall apps
and import data.
The download can be used as an upgrade on top of a current installation.
Within the downloaded package (right click see package contents) is the
actual disk image that contains the OS installation. This can be used
to create a stand alone installer (USB memory stick or DVD). This
can then be used to do a clean install.
Why a clean install instead uf upgrade? If you have been upgrading OS's
over the years and also been accumulating apps that aren't being used
and associated drivers perhaps, sometimes doing a clean install is a good
way to start fresh and eliminate the fluff that one can accumulate over
the years. Is this necessary? if a system is well maintained and kept
up to date, it usually isn't necessary.
However, some people just like to have a fresh start with a new OS
to elimate any possible issues with "old stuff".
As a note for performance, FWIW, on my 2011 Mac Mini Server
running Lion client (no Server) gives a Geekbench score of 9467.
The same machine running Mountain Lion client on a different
partition yields a Geekbench score of 9686. Ran test multiple
times booting Lion then booting Mountain Lion and the results are
the same. It's not a big difference but it is a difference and I
have noticed things being a little snappier/quicker in general.
I have SL, Lion and ML. I think I was happiest with SL. Lion is definetly slower than SL. ML is faster in some aspects. ML is installed on my new MBA which has a flash memory, so I cant compare. My MBA had Lion installed when I bought it last week and was blazing fast - 13 second bootup and 3 second shut down. today after the installation of ML, boot up is nearly the same, however, the shutdown is 13 seconds!!! I wish i stayed with Lion. Rest of the apps have no difference.