Whenever I'm in vimdiff mode, my PuTTY session slows down considerably. This is especially noticeable when I try to scroll down many lines by keeping j pressed.Why is it so slow in comparison to regular Vim running under vsplit? I realize it matches across lines and color-highlights the differences, but does that account for all the speed differences?What can I do about it? I would like to keep line matches across files (and color highlighting as well). What settings can I change to help speed up the performance of my vimdiff utility?
Why is vimdiff so slow?
ssh;putty
Do you have SSH compression enabled?  This kind of scrolling and highlighting generates a whole lot of redundant terminal traffic; compression makes a huge difference over a remote link.