Qt custom tree model display correctly but buggy and slow

I'm trying to implement a model in which different first-level parents have a child tables of different sizes. In this code there is only one first level parent index and child table of 8 by 8, and the application when displaying clearly buggy and slow, although the data is correct. What am I doing wrong?

testqtmodel.pro

QT       += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = testqtmodel
TEMPLATE = app
SOURCES += main.cpp

main.cpp

#include <QApplication>
#include <QAbstractItemModel>
#include <QModelIndex>
#include <QVariant>
#include <QTableView>

class TreeModel : public QAbstractItemModel
{
public:
    explicit TreeModel(QObject *parent = 0)
        : QAbstractItemModel(parent)
    {
        for (int i = 0; i < 8; ++i)
            for (int j = 0; j < 8; ++j)
                foo[i][j] = i + j;
    }

    QVariant data(const QModelIndex &index, int role) const Q_DECL_OVERRIDE
    {
        if (!index.isValid())
            retu QVariant();

        if (role != Qt::DisplayRole)
            retu QVariant();

        if (index.intealId() == 0)
            retu QVariant();

        if (index.intealId() == 1)
            retu foo[index.row()][index.column()];
    }

    QModelIndex index(int row, int column,
                      const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE
    {
        if (!parent.isValid())
            retu createIndex(row, column, (quint64)0);
        else
            retu createIndex(row, column, (quint64)1);
    }

    QModelIndex parent(const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        if (index.intealId() == 0)
            retu QModelIndex();
        if (index.intealId() == 1)
            retu createIndex(0, 0, (quint64)0);
    }

    int rowCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE
    {
        if (!parent.isValid())
            retu 1;
        if (parent.intealId() == 0)
            retu 8;
    }

    int columnCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE
    {
        if (!parent.isValid())
            retu 1;
        if (parent.intealId() == 0)
            retu 8;
    }

private:
    int foo[8][8];
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QTableView *v = new QTableView();
    TreeModel *m = new TreeModel();
    v->setModel(m);
    v->setRootIndex(m->index(1, 1));
    v->show();

    retu a.exec();
}