[Improvement?] Less laggy map interaction

[Elgot]

I don't know what the purpose of this is

Core.cs: 424

if (delta > span)
{
    lock (InvalidationLock)
    {
        LastInvalidation = now;
    }

    skiped = false;

    w.ReportProgress(1);
    Debug.WriteLine("Invalidate delta: " + (int)delta.TotalMilliseconds + "ms");
}
else
{
    skiped = true;
}

but if "delta > span" is changed to something else, i.e. "delta.TotalMilliseconds > 10" map interactions (like map selection with alt + mouse) feels more responsive.