Performance improvements
Some of the more interesting changes in .NET Core 2.0 are performance improvements over the original .NET Framework. There have been tweaks to the implementations of many framework data structures. Some of the classes and methods that have seen speedy improvements or memory reduction include:
- List<T>
- Queue<T>
- SortedSet<T>
- ConcurrentQueue<T>
- Lazy<T>
- Enumerable.Concat()
- Enumerable.OrderBy()
- Enumerable.ToList()
- Enumerable.ToArray()
- DeflateStream
- SHA256
- BigInteger
- BinaryFormatter
- Regex
- WebUtility.UrlDecode()
- Encoding.UTF8.GetBytes()
- Enum.Parse()
- DateTime.ToString()
- String.IndexOf()
- String.StartsWith()
- FileStream
- Socket
- NetworkStream
- SslStream
- ThreadPool
- SpinLock
We won't go into specific benchmarks here because benchmarking is hard and the improvements you see will clearly depend on your usage. The thing to take away is that lots of work has been done to increase the performance of .NET Core. Many of these changes have come from the community, which shows one of the benefits of open source development. Some of these advances will probably work their way back to a future version of the regular .NET Framework too.
There have been improvements made to the RyuJIT Just In Time compiler for .NET Core 2 as well. As just one example, finally blocks are now almost as efficient as not using exception handling at all, which is beneficial in a normal situation where no exceptions are thrown. You now have no excuses not to liberally use try and using blocks, for example, by the checked arithmetic to avoid integer overflows.