I have a column header full of text. When I zoom in the text no longer fits in the cell. What can I do? Resizing the columns and rows is out of the question as it takes too long. Why is the text sized up more than the cell itself?

It's because the Zoom function only changes the standard font of the grid (it scales the font). The cell width and height is depending on the font metrics of the standard font (see GetFontMetrics function and GetColWidth and GetRowHeight).

Unfortunately, the font metrics will not scale exactly with the zoom factor and therefore sometimes the text will no longer fit in the cell.

There is no way to get around this.