import re, datetime
for i in range (100):
  start = datetime.datetime.now ()
  re.search (
    r'(?<!\\)%[^\n]*|\\comment\{([^{}%]|\\.|%[^\n]*\n|\{([^{}%]|\\.|%[^\n]*\n)*\})*\}',
    r'\comment{\n' +
    r'\foo{bar}\n' * i +
    r'\footnote{\cite{x},\cite{y},\cite{z}}' +
    r'}%comment')
  end = datetime.datetime.now ()
  print 'n=%d:' % i, end - start