import re, time
text = "c             a                      b                      d"
pat = re.compile( "^(?!.*__)(?=[A-Za-z])[a-z A-Z0-9_]+(?<![ _])$" )
t1 = time.time()
for i in range( 400000 ):
	x = pat.match( text )
t2=time.time()
print( (t2-t1)*1000 )