Poor iTunes performance and migrating to a new computer

Q: I just finished reading your article Transferring Your iTunes Library from November 30, 2011. Very informative. I have a fairly large iTunes library – almost 90,000 songs, 500 TV shows and 200 movies, amongst a number of smaller items as well. Everything is stored on a 2TB external hard drive.

Everything I do in iTunes now is very slow. There is a pause before doing anything – scrolling through the library, updating the rating on a song, opening the song info, etc. I work in the library all the time and these delays are more than a little annoying. Is there anything you can think of that I can do to speed this up.

Poor iTunes performance and migrating to a new computer

I’m currently using a 2008 iMac with 2 GB of RAM. Assuming that one option is to upgrade my Mac, can you give me any advice to make the transition to a new iMac smooth? My biggest issue is that I have added a lot of “metadata” to my library in the way of ratings, composers, playlists, etc. and I would hate to lose this again as I did when I moved from Windows to Mac.

I’m also confused by one step in your article: If I plug in the external hard drive to the new iMac and move the current iTunes library files to the new iMac and open the current iTunes library in the new iTunes, do I just have to ensure that the name of the external hard drive is the same in both iMacs?  When I did basically this when I moved from Windows to Mac, I ended up with many exclamation marks and it took a good three or four months of re-linking the database to the “missing” files.

It was weird because probably 60-70% of the files did show up properly in the new iTunes library.

My final comment here is that I have a folder full of many album covers that iTunes uses.  Do I have to copy this folder over as well?  Or, once iTunes has an album cover, does it store it in the Media folder thereafter?

– Dan

A: It definitely sounds like an iMac upgrade—or at least a memory upgrade—is going to be required to improve your iTunes performance. Large iTunes libraries require large amounts of RAM to load and manage those libraries—“large” being defined in this case by the number of items in the library, not necessarily the overall size of those items. It’s not uncommon to see iTunes using up 1GB or more of memory for a library around your size even when performing only simple library management tasks or playing back content. With only 2GB of RAM along with the overhead from OS X and other applications running on your iMac, iTunes is going to be a bit cramped and as a result OS X ends up using much slower virtual memory (your hard drive) to compensate.

The easiest way to tell if insufficient memory is causing performance problems is to open up the Activity Monitor tool on your Mac, which can be found under the Applications’ Utilities folder and select the “System Memory” tab at the bottom. A lack of “Free” memory (the green section) is one possible warning sign that you have insufficient RAM for whatever apps are currently loaded, particularly if the red “Wired” and yellow “Active” sections are occupying the majority of the memory pie chart. However, the blue “Inactive” segment represents memory that has previously been used by other apps, but is now available to be reallocated if needed, so the real indicator of a memory-related performance issue is a high number of “Page outs”—this is an indication that your iMac is writing information from “real” memory (your RAM chips) to “virtual” memory (your hard disk) because it doesn’t have enough real memory available to work with. Since a hard disk is much slower than your RAM chips, every time iTunes (or any other app) needs to access something from virtual memory you’re going to see performance lags.


Poor iTunes performance and migrating to a new computer

Obviously, moving to a whole new iMac with a faster CPU and more RAM is going to make your entire experience much smoother overall, but you could probably get away with simply increasing the RAM in your existing iMac if you’re not ready for the expense of a whole new computer right now. Even 4GB of memory should provide a noticeable increase in performance for iTunes, provided you’re not loading other memory-intensive apps at the same time.

If you do go the route of getting a new iMac, transferring the library should actually be a much smoother process than your transition from Windows.

One of the problems with moving an iTunes library between different operating system platforms is that the file systems—things like drive names, pathnames and filenames—are structured in a completely different way between Windows and Mac OS X, so there’s really no way to be sure that iTunes is going to be able to find everything properly once you move it over to the new computer, and it’s important to keep in mind that the iTunes database stores full path names to all of your media files.

For example, you may have had your music in a folder named “D:Music” on your Windows PC, but there’s absolutely no way to even create a folder with that type of naming convention on Mac OS X, which uses drive names instead of letters, forward slashes (/)  instead of backslashes () and mounts external drives under a /Volumes folder. So if you take an external drive that is “D:” on your Windows PC with a volume label of “EXTHD” and plug it into a Mac, the path of “D:Music” from Windows becomes “/Volumes/EXTHD/Music” on the Mac. You can probably see how this would confuse iTunes, which will still be looking for its media files on a drive that can’t possibly even exist on the new computer.

On the other hand, moving between two computers running the same operating system is a much smoother process because everything remains the same in terms of the file system structures. Take your drive named EXTHD from one Mac to another and it will generally still be mounted under “/Volumes/EXTHD” and therefore all other pathnames will remain the same. The only exception to this is in the case of a name conflict—for example if you already had a drive named EXTHD plugged into your Mac; in that case, the second drive is assigned an additional number (e.g. “EXTHD1”) to distinguish it.

Moving your iTunes library over to a new iMac should be as simple as copying the entire “iTunes” folder from within your internal hard drive’s “Music” folder to the same location on the new iMac. You can even use your existing external hard drive to facilitate the transfer assuming that it has enough free space available. This database will contain full paths to all of your media content on the external hard drive, but since the external hard drive should be assigned the same path on the new iMac, it will be as if nothing ever changed.

In fact, for the most part iTunes won’t even know that it’s running on a different computer, since everything it needs should still be accessible.