Seek a new contact on the send mail is broken slow (on ie.)

About 8k contacts. send an email, try to add a CC or BCC, type the first letter and it's waiting for a rely forever. Type more letters and it goes completely banana on IE at least.

I suggest :
1) add a minimum of 2 chars before doing an ajax request
2) Increase the delay before firing a new request.

Is this the same autocomplete than for the searches ? Seems to behave not as good ?