word-break: break-all sometimes fail on really long text (~10000 characters), why and how to fix it?

I simple have a span element, with random letters (a~z) on it, around 100000, no spaces. I used word-break: break-all, and it worked as intended, the text would not overflow. But... There are random points in the doc where some letters do overflow outside. On this amount of text, it usually happens 3 or 4 times in the whole doc on random points. The screenshot shows that all text is perfectly aligned (cause it is a monospaced font) except on these random areas where a couple slip outside... Is that just the browser failing on the huge amount of characters? Or something else? If so, is it fixable?