title: Vim response quite slow
body: <p>If I open a file containing 5,000 lines of code and continue to input, I found that my vim became very slow, it displays my input after about 1s. </p>
  
  <p>It even won't become any better after I start up with <code>--noplugin</code>. But after switching my  <code>.vimrc</code> file, everything gets fine again. The <code>.vimrc</code> file is written by myself and after checking for some time, I still can't locate the error. I have clear all the key maps, but the problem still exists.</p>
  
  <p>So can you give my any advise or tell my how to debug in vim? I found there is a debug option but can't get how to work.</p>