POS receipt printing and cash drawer kick are very slow

When we scan items in POS the performance is acceptable.  Unfortunately, when we complete the sale, after entering the payment the POS waits 3-4 seconds before the receipt prints, and then another 3-4 seconds before the drawer kicks open (for cash transactions).

We already have Pooling=true in the config file.

Does anyone have any experience trouble-shooting this type of performance problem?  Any suggestions on what to check first?

All of our POS systems exhibit this problem (18 across 4 different stores).  The POS database is on a high-end server, and indexes have been re-built or re-organized.

Thanks in advance for any advice.