As millions of Mac users continue to adopt OS 10.8 Mountain Lion, it’s clear most user experiences are really great. There’s, in fact, a perceptible performance boost, most probably to do more efficient graphics drivers. One test from Ars Technica indicated a modest performance increase that would reveal itself with snappier performance.

That would explain why I’ve observed such improvements. As an example, when moving audio tracks through the timeline in Amadeus Pro, an audio editing app, I can confirm that the action is smooth, fast, fluid. It was ragged under Lion. Clearly Apple has done a lot of work behind the scenes.

But that doesn’t mean there aren’t any problems. There are published reports that Apple is investigating the mysterious 50% reduction in battery life on some MacBooks right after installing Mountain Lion. As usual with such issues, it’s not an across-the-board phenomenon, which makes it that much more difficult to nail down.

Now I did encounter one issue after an otherwise flawless Mountain Lion installation that may explain why battery life may have taken a hit for some of you. In my case, it was a runaway process, involving Contacts, which kept CPU usage very high on a late 2009 iMac, with a corresponding performance dip. The problem revealed itself clear as day in Apple’s Activity Monitor app, which you’ll find in the Utilities folder. In short, if something like this happens on a Mac note-book, if the CPU is working overtime for some reason, battery life is going to be reduced.

In my case, it took just a little voodoo to set things right. The problem appeared to result from Contacts constantly polling iCloud for updates. First I logged out of iCloud, accepting all the dire warnings about the consequences to my address book, deleted all the Contacts preference files (which still bore the AddressBook label for some curious reason), and logged back into iCloud. The runaway process, ABAssistantService, was history, and CPU use was restored to a more normal level. Suddenly Mountain Lion acted as if on steroids.

I read another report of a similar runaway process, involving the Calendar app, with the same symptoms. A little finagling with iCloud, and the problem vanished. I wonder if such issues explain why battery usage is higher than it should be on some Macs. In passing, I haven’t observed any noticeable decline in the battery life of my 2010 17-inch MacBook Pro, nor did I see evidence of anything taking an unusual proportion of memory or CPU reserves.

That doesn’t mean that these iCloud related issues are causing all of the battery life problems some of you are reporting. But it is an example of one possible cause for such symptoms. There are also reports that some users are experiencing severe system slowdowns after installing Mountain Lion. I don’t know if they have gone as far as I did to see what might be taking an excess amount of system resources, but it does make me curious.

If Apple releases a 10.8 update in the near future to address battery life problems and system slow-downs, I will be curious to see if they devised a fix that keeps those runaway processes in check.

In the meantime, if your Mountain Lion installation has been flaky, take a look at Activity Monitor to see if something is a little too energetic with system resources. The symptom will usually involve something bearing an arcane name constantly grabbing 100% of CPU horsepower. If quitting the process, which is easy in Activity Monitor, results in its mysterious return after a few seconds, you may just want to do an online search of the purpose of the runaway process, which may give you some clues as to what’s responsible.

Point-zero issues of this sort shouldn’t necessarily deter you from installing Mountain Lion. The problems appear to affect a small number of users, and the runaway process phenomenon doesn’t seem terribly difficult to solve, if that’s the cause of the other reported symptoms. But if it all seems too daunting for you, you might as well contact Apple support or visit the Apple Store Genius Bar.

As OS releases go, however, Mountain Lion appears to be better than most of Apple’s recent OS upgrades. Being able to get superior performance with a new system installation is always a good thing.

Of course, there are always potential incompatibilities with someone else’s app. If you’re hesitant, maybe you want to consult the Roaring Apps an extensive list that indicates whether apps are fully or partly compatible with Lion and Mountain Lion.

Yet another potential problem with Mountain Lion concerns possible lost features. One obvious example is Web Sharing, a Sharing preference that activates an Apache server on your Mac, which disappeared in OS 10.8. This is not necessarily intended for running a regular Internet server — that’s the province of the Server version of Mountain Lion. But it’s good for testing your site.

Fortunately, the loss of Web Sharing, while it doesn’t make sense, is easily fixed. There’s a piece at MacFixIt that explains how it’s done via a few Terminal commands. It’s not so big a deal, but you have to wonder why Apple thought this feature wasn’t worth retaining, since switching it on or off is such a trivial matter.

This article was posted on Tuesday, August 7th, 2012 at 12:00 AM and is filed under News and tagged with: Apple, Apple Inc., Ars Technica, Calendar, Contacts, CPU, iCloud, iMac, Lion, Mac Os X, Macbook Pro, Macfixit, Macintosh, Mountain Lion, Web Sharing.