User talk:Laeeth

0. DMD flags:-O -release -inline -noboundscheck

  LDC -O5 -release -inline -boundscheck=off
  GDC -O3 -frelease -finline -fno-bounds-check

0a. Use LDC or GDC

1. Profile first; then optimize. For DMD: dmd -profile; also perf on Linux and AMD CodeAnalyst

2. Do foreach (y; 0 .. height) not foreach(y; (iota(height)))

3. Be careful with foreach on arrays of structs, because it performs copies that are slow if the structs aren't very small.

4. Sometimes in inner loops it's better to use a classic for instead of a foreach.

5. Be careful with classes, because on default their methods are virtual. Sometimes in D you want to use structs for performance reasons. Otherwise make all methods final

6. GC: Minimize situations where there's a lot of allocations going on while the GC is enabled because that will fire up the GC more often than is required and it can slow down your app significantly; A 2x or more performance penalty is certainly possible. It can also make performance unpredictable with large delays at inappropriate points in the execution.