Your situation is word-for-world the exact same issue myself, fellow graphic designers, and IT department are facing.
I have been aware of this problem for well over a year now, and have been in constant search of a proper, "actually works" solution. No such luck as of yet.
I have also been aware of the ExtremeZ-IP option others say works for them.
In favour of trying to remedy the problem with a non-paid solution first however, I searched the deepest depths of Google to no avail.
I have been in phone contact with an Apple IT rep, and to be honest, they are oblivious of the issue, or are ignoring the fact that this is a real issue.
In the move forward to advance with technology, we must, and have upgraded OS X to Mavericks, and in the future, Yosemite.
The design department I work in has a handful of designers. We all use Macs. Our workflow is setup so that we save all of our work, Photoshop, After Effects, Cinema 4D, and any other graphic files are saved on a central file server so that other designers can access, and edit each others files at any time from any Mac. We work in a live television news environment, so searching of these files in a lightning fast manner is absolutely crucial.
Before this fiasco, the Macs ran on OS X 10.6.8. The Windows server holding our files is running Windows NT 4.
With OS X 10.6.8, doing a spotlight search for filenames of previously saved graphic files was quick, reliable and well, just worked.
Since the upgrade to Mavericks, this new SMBv2 protocol is what I believe to be the culprit of this evil. In fact, searching is just half the battle now.
ANY server interaction it seems makes the Mac slow, unresponsive, and sometimes F's it up so badly you have to push the power button!
For example. In Photoshop, naving to a folder on the server to save a file, it could sometimes take 5 or more minutes for the folders to even populate, and then sometimes just as long to save the file.
The problem with ALL of the solutions others mention is that they are missing the point. You should NOT need a Finder replacement. Finder, is a core, essential part of OS X. (Imagine Windows without Windows Explorer!) Finder must and SHOULD "just work". Finder replacements like EasyFind only search in list view. Designers search visually - aka, thumbnail view. Finder Replacements also do not replace File-Save or File-Open windows in apps, like Photoshop, or AI, AE or anything else. There is no integration that way.
So, recently speaking to the IT people managing our Macs, it looks like we might perhaps opt for a local, Mac-friendly server option.
I can't even to begin to describe the frustration this has cause us. This has single-handedly changed my perception of Apple, and their view of enterprise support and creative professionals. It reached a point where I said, I'd be happy to switch to a PC. And for me to say that....
So, Apple, if you read these boards, know that you have let a huge chunk of your user base down. Royally.
it's nearing 2015. It's time to "Think Different".