An Unknown Error Occured (Lightroom 4)

Question

I have just upgraded my PC from Windows XP to Windows 7 and from Lightroom 2 to Lightroom 4 (purchased in the past week - not the beta version). I was having one or two issues with LR2 and was looking forward to better performance with my shiny new system, running on a quad core processor and effective 4 gig of RAM.
Straight from the off when editing images in the 'Develop' module, the responsiveness seemed slower than before when applying presets, zooming in and out and using the adjustment brush. Surely a system of this spec should run Lightroom no problem (I am editing Canon 5D MkII RAWs sized around 35Mb)?
And more worryingly, a couple of times LR4 just refused to apply a preset and was hanging. And then when just flicking through and applying presets I've had the dreaded and disconcertingly vague 'An Unknown Error Occured' twice in the space of an hour.
Please help!!!

Answer 1

John, I'm sorry your thread got missing.  This is a user-to-user forum, not an Adobe Support channel.  While Adobe Employees do drop in here now and again, most of us are users like yourself, freely volunteering our time to help others.  Once a thread disappears down the listing, it's not likely to be seen again, so please feel free to post again to see if someone can help.
There were some performance issues in 4.0, which unfortunately were not picked up before release, but Adobe pulled out all the stops to make a fix available as soon as possible, with the first release candidate available about 3 weeks after the initial release.
Reading the forums now, you'd get the idea that everyone's still suffering from performance issues, but then, most people don't flood to the forums to post how well things are working.  Unfortunately a small percentage of users are still affected by performance issues, and work continues to figure out what's different about their machines.
Sharon, you didn't mention your system specs?  Perhaps there's something we can help you tweak to improve things?
We'd all love our software to run quicker without ever having to upgrade our computers.  Unfortunately technology doesn't work like that.  We feed our computers ever larger files, and expect them to do increasingly complex calculations, but that does come at a cost - either in time or in upgraded systems.
PV2012 will be slightly slower because technology has advanced - it's doing much more complex calculations than earlier Lightroom versions, which does take additional processing power.  The older calculations are still there, listed as PV2010, and if the performance is causing problems, using those older sliders is another option you could consider.  There are other things you can do to help, particularly on mid-spec computers, such as minimizing use of the most processor-intensive tools (i.e. lens corrections, spot removal, etc.)
Adobe will continue to work at finetuning the PV2012 performance, as well as trying to fix the mystery performance issues that some are seeing.