This would be a little faster:
<?php
/* ImageDiv snippet */
return empty($modx->resource->getTVValue('homepage_image'))
? '<div>2 columns</div>`
: `<div>1 Column</div>`;
I think it would be a little faster yet if you replaced 'homepage_image' with the ID of the TV.
default and isempty won't really help you because in your case they do the same thing as isnot.
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