u might not follow that explanation though, so i'll write it simpler:
computer data is often stored in arrays (basically a bunch of stuff in a row). arrays have a fixed size in memory. sometimes they get full. the basic solution is you make a new, larger array, and copy all the old data into it.
in comp sci classes they generally teach (or maybe only used to, dunno) that you should make the new array double the size of the old. you want to try not to waste too much memory by making it bigger than needed, but also increase the size enough not to have to do this very often, because copying over all the data is expensive.
anyhow, if your array takes up 1 unit of memory, and you double, the new one takes 2 units of memory, with a gap of 1 empty unit behind you. next doubling, your array takes 4 with a gap of 3. then takes 8 with a gap of 7.
see the problem? the array never fits into the gap.
if you increase the array by a factor of 1.5 instead, it will fit into the gap.
actually works pretty fast. 1.5 with 1 gap. then 2.5 gap and array is 1.5*1.5=2.25 ... already fits.
anyway, it's a neat improvement.