I've found the computer benchmarks game to be an interesting distraction for a while (I particularly like how they're rigorous about telling you what's happening behind the scenes), and have been particularly amazed to see the relative changes in performance in particular code bases as things like JIT compiling have been integrated into them. The rest of the site's statistics (ex: n-body for same x64 http://benchmarksgame.alioth.debian.org/u64/performance.php?test=nbody ) are pretty cool, but I find these code vs time shapes to be some of the most concise representations for per-language efficiency.
Code-Used vs Time-Used Shapes for Computer Benchmarks Game | Heykuki News