I have this python script, in one line I have a 1000 character long string. I have syntax highlighting on, vim hangs on this line. If I change the file extension to c++ than it works. I suspect problems with syntax highlighting plugin is is causing the hang.
Can this be fixed somehow?  I'm using vim version 7.4.52
Overly long lines can dramatically slow down Vim's syntax highlighting; usually, this is a fault of the syntax script, and you should inform its author (found in the $VIMRUNTIME/syntax/python.vim script header).
Vim 7.4 includes the :syntime command, which greatly helps with troubleshooting and finding the problematic regular expression.
It might help to :set synmaxcol=... to a value lower than the default 3000.
Vim python syntax highlighting hangs for very long lines