Number of Columns and Update

This may fall into the category of over-optimization but I've become
curious.

I have a user table with about 14 columns that are all 1:1 data - so they
can't be normalized.

When I insert a row all columns need to be set. But when I update, I
sometimes only update 1-2 columns at a time. Does the number of columns
impact update speed?

For example:
UPDATE users SET email = ? WHERE id = ?;

I can easily break this up into logical tables like user_profile,
user_credential, user_contact_info, user_summary, etc with each table only
having 1-4 columns. But with the multiple tables I would often be joining
them to bring back a collection of columns.

I know I'm over thinking this but I'm curious of what the performance trade
offs are for breaking up a table into smaller logically grouped tables.

Thanks.