Double replace or single re.sub?

[Iain King]

I have some code that converts html into xhtml.  For example, convert
all <i> tags into <em>.  Right now I need to do to string.replace calls
for every tag:

html = html.replace('<i>','<em>')
html = html.replace('</i>','</em>')

I can change this to a single call to re.sub:

html = re.sub('<([/]*)i>', r'<\1em>', html)

Would this be a quicker/better way of doing it?

Iain