>>Can you try scrolling with following configuration?
>>
>>  (setq mouse-wheel-scroll-amount '(1 ((shift) . 5) ((control))))
>>  (setq mouse-wheel-progressive-speed nil)
>>
>>Those are two that are already suggested by Eli.  Please try both at
>>the same time.

> I've tried these both at the same time already. As I've said -
> scrolling down is a bit laggy (and it eats the CPU and turns on my
> fans up high). And scroll up is much laggier. It's when I scroll
> slowly.

I got what the laggy meant.  I think we want the second spin to be
coarse.  How about something like below?