If you are currently including a PDF of the customer's invoice so that the customer's order details can be sent you can now use the following macro in your emails.
[%ITEMS_ORDERED%]
This adds the items ordered details (similar to the Actinic email).
This will increase the speed of sending emails (as a PDF does not have to be created).
Also you should check your email log settings as this can slow down your sending of emails (as the logfile gets very large). You should check that your settings are set to New logfile each day if you don't clear down your email log. This is shown below:
If you tick 'New logfile each day' (in the Email setup dialog). Your current logfile is probably getting very large now and 1 company has reported an issue with this.
Thanks
Pat.