Some of the most interesting performance and implementation changes -
- Go routine stacks now use a contiguous model instead of the old "segmented" model
- GC is faster - uses concurrent sweep algorithm, has better parallelization and larger pages; leading to 50-70% reduction in GC pause times. It is also now precise when examining values on the stack too.
- Runtime handles defers more efficiently
- Race detector is around 40% faster
- Regexp (regular expressions package) now has a second, one-pass execution engine making it faster for certain simple expressions
- sync.Pool - a new type that provides efficient mechanism for implementing caches whose memory can be reclaimed by the system
- Iterations over small maps no longer happen in consistent order; this is to avoid developers writing code that depends on map iteration order, since such code would work well only on some systems
- godoc can now perform static analysis of the code it indexes
- misc/benchcmp (benchmarking tool) has been rewritten as a Go program
- Compilers and linkers have been refactored; the instruction selection phase has been moved to the compiler, which can speed up incremental build times for large projects
- gc toolchain now supports Native Client (NaCl) execution sandbox on 32- and 64-bit Intel architectures. Note that Go 1.3-generated binaries still cannot be run directly by Google Chrome.
You can read more about all the changes in the release notes.