Less than a month after releasing later version of Luxrender, is new update released. According to Luxrender forum what really motivated this new release is the Blender 2.64 release which was incompatible with the LuxRender v1.0 exporter. New version brings a speed improvement ranging from 10 to 40%, a brand new, more realistic sky model and various improvements. This version should be also best to answer your questions in the forums or in the bug tracker.
Changes since 1.0:
- huge speed up with CPU rendering (measured from 10 to 40% improvement, mostly noticeable when using instances)
- new sky2 light using Hosek and Wilkie just released model
- render queue fixes when using network rendering
- fix haltspp when using SPPM
- new nsamples parameter to the distant light to match other lights and be adjustable with advanced light sampling schemes
- don't add an extra extension when saving jpeg or tiff files
- fix light groups LDR saving
- use a new cache directory in the user temp directory for network rendering to prevent denied accesses when downloading files
- prevent out of bound interpolation with the mix material
- network rendering fixes
- fix area lights consisting of several 100000 faces
- updated luxrays to support more LuxRender features in core
- architectural glass fix in SLG
- render noise threshold halt condition in SLG
- various fixes and improvements
Source: LuxRender