I've been receiving a few emails of people concerned about the performance of the Mac mini under Mac OS X 10.4 (Tiger) - especially with regards to support for Tiger's Core Image technology. Core Image is basically a cool label for GPU rendered UI, whereas OS X 10.3 today is CPU rendered but GPU composited (if you have an appropriate GPU). The problem with the Mac mini is that the Radeon 9200 it has in it is based on the RV280 core, which is not a fully floating point GPU. The question then becomes, will Core Image require Shader Model 2.0 or will the 9200's Shader Model 1.4 suffice?

I tend to believe that Apple will have essentially the equivalent of multiple rendering paths for Core Image, with some features made available to Shader Model 2.0 GPUs that aren't made available to SM 1.x GPUs and the default case being revert to a fixed function, non-Core Image enabled UI. But that's just an assumption, what I really want to know is if anyone has tried the latest Tiger builds on the mini and if so, is Core Image support enabled and is it fast?

The other problem with the mini's Radeon 9200 is it's only got 32MB of memory attached to its 64-bit DDR memory bus. I'd expect Core Image to be more GPU memory intensive than Panther's rendering and compositing engine, which means that memory size and bandwidth are important. The memory bandwidth aspect of things should be ok, but it's the memory size that I'm worried about. If you've read my review you'll remember that I mentioned at resolutions greater than 1280 x 960 Exposé started to get choppy. If the 9200 is in some way supported by Core Image, I'd hope that the minimum resolution at which you can still have smooth Exposé and Dashboard functionality remains as high as it is currently under Panther.

The reason this is something that concerns me now is simply because given the popularity of the mini, I want to make sure that recommending it won't leave users with a less than satisfactory experience in a handful of months when the next version of Mac OS X is released. Any first hand feedback? Post it here or drop me an email.