Help optimizing code?

[Uknown]

On Tuesday, 2 January 2018 at 07:17:23 UTC, Uknown wrote:
> [snip]
> 0. Use LDC. It is significantly faster.
> 1. Utilize the fact that the Mandelbrot  set is symmetric about 
> the X axis.You can half the time taken.
> 2. Use std.parallelism for using multiple cores on the CPU
> 3. Use @fastmath of LDC
> 4. imageData.reserve(width * height * 3) before the loop
> 5. [1] is a great article on this specific topic
> [snip]

Forgot to mention that since you already know some of the edges, 
you can avoid unnecessarily looping through some regions. That 
saves a lot of time