Most likely just another bug in Nik's code.
Check with them for updates.
Thanks, Chris. I know that it's probably something like that, or a problem with Norton. Running as Admin is probably just getting around whatever the problem is. The only trouble with these weird problems is they are so hard to pin down. I'm still puzzled as to why Photoshop seems much more responsive in Admin mode. But it might just be my perception of it running faster.
I'm not saying Norton is your problem, but I haven't heard good things about Norton software in a long time, unfortunately.
I always recommend Avast! antivirus to people. The free version is very good in itself, and they offer a more comprehensive Internet Security version as well.
I don't know how technically-oriented you are, but if you do understand how things work fairly well and have taken measures and adopted good practices to avoid running malware, there is the possibility of just shutting off UAC (MIcrosoft User Account Control) if its operation continually gets in the way of your completing your work. Typically, most people just get in the habit of confirming whatever prompts come up anyway, which defeats most of the protection UAC can afford.
I just discovered something very weird. I normally invoke Photoshop (CS6) by going to Bridge and selecting an image and double-clicking it. CS6 will load and load the image I selected. If I then invoke the Silver Efex Pro (SEP) plugin (from within CS6 using the FILTER menu) it takes a nose-dive on performance and takes about 5 times as long to process. If however I load Bridge, then load CS6 manually from the taskbar (not in Admin mode) Ithe SEP process runs extremely fast. I just tried this several times and it's the same evey time - it works fine when I load CS6 manually.
Is there a difference or any issues around how Photoshop is loaded? Is Bridge perhaps failing to do something when it invokes CS6 for you?
As Noel said, your Norton software may contribute to your issue, but on a more general level these are probably simply local port issues that affect communication between the various processes. Both Bridge and SEP may unintentionalyl be using the same port connections and this creates a bottleneck. Naturalyl it won't happen when you launch PS outside such a local loopback connection because then eitehr never a port connection is even established or a different port may be used.
Thanks, Mylenium. I'll load it manually in future. I like your 'brief bio'