I'm using Lightroom 4.1 RC2 on 64bit Windows 7. My C: drive is an SSD and only has about 8GB free. My catalog and Lightroom cache are both configured to live on my F: drive however, so I wouldn't have thought this would be a problem.
What I'm finding is that after an hour or so of editing (in the Develop module only), I run out of space on my C: drive which causes Lightroom to exit, and other general system instability (eg Windows Explorer dies). It looks like Lightroom is creating large files in my temp directory (C:\Users\<username>\AppData\Local\Temp) called eg cr_sdk_03182513.tmp.
What are these files for and why do they get so big? Can I configure Lightroom to store them elsewhere (ideally without relocating my temp dir)?
Thanks Dorin. I'd performed a quick search of the forum but only found a few comments vaguely alluding to the problem, I missed these two threads.
I realised I could relocate my tmp directory but figured the behaviour looked more like a bug in LR than sensible use of the temp dir. Sounds like I don't have much choice other than to live with it for now; I'll move my temp folder to a different drive and hope it gets addressed in an upcoming release.