Answer by LeftRight92 for Linear Feedback Shift Register efficiency

Have gone with the following solution:

public int DoShift()
{
    //Remember falloff, shift register, add new bit
    int result = Contents & 1;
    Contents = (Contents >> 1) ^ 
        ((CountBits(Contents & tapSequence) % 2) << (length - 1));
    return result;
}

//Brian Kernighan method of counting bits
public static int CountBits(int value)
{
    int count = 0;
    while (value != 0)
    {
        count++;
        value &= value - 1;
    }
    return count;
}

Additionally, I may also attempt some to run elements of the broader programme in parallel.