A couple of notes first.
8 editors on Mac Pro's (ranging from 3,1 to 5,1) accessing media stored on a SAN via 10Gb ethernet. The SAN drives are mounted via SANmp. The 10Gb ethernet connection is created with globalSAN iSCSI Initiator and Xtarget.
Performance has been spotty when playing back video, no matter which software is used (even tried Final Cut Pro 7, which used to be our editing platform). File transfers are very fast however, which likely points to in issue outside of Premiere Pro and more of an issue with the performance of the SAN or the 10Gb ethernet connection... anyway.
Only recently did Premiere crash when I import media from the SAN. The same files import and playback without any issue once I have copied them to local storage (an internal 7200rpm hard drive). I even tried replacing the a local file with its twin on the server, which also causes Premeiere to crash (spinning beachball of death that never goes away). After Effects, Photoshop, and other programs have no issue opening/importing the very same files from the SAN.
This is only a recent issue, too. I completed a project last week that mixed h.264 video with native RED video and WAV audio. The only issue with that project was choppy playback, even after rendering the timeline, which is also baffling to me... It seems like it is an issue specifically with Premiere accessing media from the SAN, but I'm not sure about that since it wasn't an issue with a previous project. My edit machine is bound to the company domain (internal network) and internet is accessed through the same ethernet connection. I'm assuming this only contributes even more to the playback issues that have been observed.
Specifics on my particular machine:
8 core Mac Pro 3,1
OS X 10.6.8 (yeah, I know. upgrade already, right?!)
In general, PPro does not work well (if at all) if the files are on anything other than a "local" drive (internal or direct connect external)
-see messages #1 and #3 in http://forums.adobe.com/thread/771151
-you MUST give all users administrator accounts to use Premiere
-and especially Encore dual layer http://forums.adobe.com/thread/969395
-#5 Server 2008 is UNsupported http://forums.adobe.com/thread/851602
-a work around, of sorts http://forums.adobe.com/thread/957523
-and not on a "domain" http://forums.adobe.com/thread/858977
Someday... a possible solution
Adobe Anywhere http://www.adobe.com/products/adobeanywhere.html
-launched at NAB 2013... final availability expected some time in 2013