title: vim randomly breaks syntax highlighting
body: <p>When working on a remote server with rather large ping times, the syntax highlighting suddenly and seeming randomly breaks. When that happens, it looks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/q2sS0.png" alt="enter image description here"></p>
  
  <p>The syntax highlighting is fine til line 24, after that everything is grey. I can fix it by randomly scrolling around or close open vim. But I can neither reproduce the problem, nor reproduce the fix.</p>
  
  <p>This does not happen when I work with exactly the same version of vim and exactly the same .vimrc. Therefore I suspect there's something wrong on the server. Especially I suspect the problem might arise due to the long ping times (~ 170 ms).</p>
  
  <p>Did anyone see a similar behaviour?</p>