Why SVG images using <path> elements create larger file sizes than those using <defs> elements?

[sdespont]

I've compared two SVG images: one created using the element (31kB) and the other using and elements (76kB).

I don't understand why the SVG image created with is larger (19kB) compared to the image (15kB). What could be causing this discrepancy?

I'm asking this question because I'm writing files with numerous SVG images. I assumed that using a more powerful and compact format like would result in smaller file sizes. Are there any options I could apply to achieve this?

require_once('tcpdf_include.php');
$pdf = new TCPDF('P', 'mm', 'A4', true, 'ISO-8859-1');
$pdf->AddPage();
$pdf->ImageSVG("images/5.0.8.svg", 100, 100, 46, 46);
$pdf->lastPage();
$pdf->Output(__DIR__.'/example_006.pdf', 'F');