Parallel Rogue-like benchmark

[bearophile]

Joseph Rushton Wakeling:

> How does the speed of that code change if instead of the Random 
> struct, you use std.random.Xorshift32 ... ?

That change of yours was well studied in the first blog post (the 
serial one) and the performance loss of using Xorshift32 was 
significant, even with LDC2. I don't know why.

Sometimes even moving things (like the Xorshift struct) in 
another module changes the code performance. Performance 
optimization is a bit of an art still. In theory such cases 
should be studied, and the performance loss should be understood 
and fixed :-)

Bye,
bearophile