def get_recommended_simplification_params(warning_len):
    """Return the recommended geometry simplification tolerance and buffer.

    These settings are based on the number of warnings present, and designed
    to prevent the map interface from lagging if many warnings are present.

    Parameters
    ----------
    warning_len : int
        number of warnings in the warning list.

    Returns
    -------
    dict
        {'tol': float, 'buf': float}.
        Parameters which determine the degree of shape approximation
        recommended for mapping.

    """
    if warning_len < 10:
        return {'tol': 0.000, 'buf': 0.000}
    tol = (round(warning_len, -1) - 10) * 0.000025
    buf = (round(warning_len, -1) - 10) * 0.00005

    return {'tol': tol, 'buf': buf}