vim long line slowness

Yes, it is very slow to have a long line copy or move within vim, which mostly due to the syntax highlight procedure as explained
Just as mentioned, three enhancement methods are:

1. Turn off syntax highlighting with :syntax off.
2. Limit syntax highlighting with :set synmaxcol=150 or some other value.
3. Break down your long line in smaller chunks with :s/\s<a/<C-v><Enter><a.

Method above could address the long line slowness problem, I tested it already.