Optimizations:

1. CPU Parallelism: C# Parallel Library
2. Cache Optimizations: Dual-Pivot QuickSort
3. Instruction Optimization: Insertion Sort
4. Compiler optimizations: C# Optimize Code

Notable performance improvements.

Using NuGet VxSort (AVX) package for reference.

Sorting 100'000'000 random integers in 2182 [ms].

Sorting 300'000'000 random integers in 6738 [ms].

Visualing results in accompanied Excel file.