> is there any better way to do
> it with a single developer for
> a website that serves millions
> of people a day?
No, the other reason they're using this is to make it so annoying that you'll spend $20/yr to buy a 4chan pass to bypass it.If you're not making your free website annoying to drive revenue there's obvious ways to make it less annoying.
E.g. keep the annoying captcha, but don't show one again for the lifetime of a cookie, validate users who can make a money transfer of $0.01 etc.