I tried running it in a VM with 8GiB and it was still struggling at times

Superman’s kryptonite is still unkown, unfortunately.
Scientists have speculated that understanding the physiology of Subman (Superman’s greatest threat) may help us find it, but so far polite requests for non-invasive experiments have been declined and we cannot, in good conscience, forcefully subject him to them.

When dealing with base 10 representations, multiplying by 10 is a simple matter of adding zeroes;
dividing numbers that end with a zero by two is (usually) an afterthought;
doing both operations in that sequence is (usually) equally trivial, the only effortful thing I have to do is adding or subtracting a multiplicand, once or twice or thrice.

It’s not easier than having the result imprinted in my memory, but it cuts away ~ three quarters of the table.

Nope, went through “(6 × 5) + 6”. Slightly slower, but much more flexible since you can do that with any (base 10 representation of a) number that has a reasonable number of digits.

You should elaborate a bit, I can get two possible interpretations of this - one which I agree should be a more popular opinion, and one which I believe is nonsense and should be made fun of.