Mail lags when hitting return key

I am running latest version of Mountain Lion. I have seen threads on general mail lagging - but none triggered solely by hitting return key..

When I am composing an email, Mail lags whenever I hit "return/enter" key after typing a message. It also takes a couple seconds to bring the "reply" window up - often times pinwheeling for a bit..

If I hit return on a blank line it does not lag. Only when there is text on the line I am hitting return from.

No other program does this..

I have tried to boot in safe mode - no help

I have Console open and see no issues either.

A restart or quit does not fix it - neither does a disk repair.

I have several IMAP accounts and iCloud - problem exists when sending from all of these.

Any advice would be great!