FAQ: How to generate SVG files smaller than 15KB for GT?
Enable SVG minimization.
Optimize vectorization parameters as much as possible to reduce the output size as much as possible. For example select 'clipart' and a one of the lower detail options. Reduce colors as much as possible.
Download vectorization result as .zip file. This file archive contains the vectorized SVG file which is most of the time larger than 15KB. But this archive also contains the vectorization result as multiple splitted SVG files each smaller than 15KB.