count "empty space" right/left in a 2D vector efficiently

I have a grid of the form std::vector< vector<int> > grid (rows, std::vector<double>(columns)); which is a member variable of a class. The grid has stored values from the set {0,1,2, ... , 9}. Imagine if I go through the grid and at every position where grid[row][col] != 0 I need to know how many zeros are to the left and to the right before again grid[newRow][newCol] != 0 is fulfilled (to the left/right means in this row, so one has to iterate through the column index). For the moment I do it with the following two functions:

int countLeft(unsigned int rowIndex, unsigned int colIndex) {
    int left = 0;
    for (signed int i = colIndex-1; i >= 0; i--) {
        if (this->grid[rowIndex][colIndex] != 0 && this->grid[rowIndex][i] == 0){
            left++; 
        }
        else
            break;
    }
    return left;
}

int countRight(unsigned int rowIndex, unsigned int colIndex){
    int right = 0;
    for (unsigned int i = colIndex + 1; i < this->grid[0].size(); i++) {
        if (this->grid[rowIndex][i] == 0 && this->grid[rowIndex][colIndex] != 0) {
            right++;
        }
        else
            break;
    }
    return right;
}

Running the Performance wizard on VS2013 I found out that these two functions are slowing down my program significantly. Therefore my question, how I could improve my method of knowing the zeros to the left/right, without counting every time. Thanks in advance.