I assume that you mean mouse scroll speed (since keyboard scrolling is welcome and should not change across platforms / versions unless you change your .vimrc)
From http://vimdoc.sourceforge.net/htmldoc/scroll.html#scroll-mouse-wheel
You can change the default behavior by matching keys. For example, to make the scroll wheel move one line or half a page in normal mode:>
:map <ScrollWheelUp> <CY> :map <S-ScrollWheelUp> <CU> :map <ScrollWheelDown> <CE> :map <S-ScrollWheelDown> <CD>
You can also use the Alt and Ctrl modifiers.
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