Vim scrolls very slowly when a line is too long

try following:

" Syntax coloring lines that are too long just slows down the world
set synmaxcol=128

else i recommend speeding up vim by:

set ttyfast " u got a fast terminal
set ttyscroll=3
set lazyredraw " to avoid scrolling problems

This is a known problem with Vim and very long lines. I see three solutions:

1. Turn off syntax highlighting with :syntax off.
2. Limit syntax highlighting with :set synmaxcol=200 or some other value.
3. Break down your long line in smaller chunks with :s/\s<a/<C-v><Enter><a.

In this particular case I'd recommend solution 3.