I have made some pretty interesting finds the last hour. First I changed repeat to one and YES the inter-key delay was lowered to an acceptable rate. One problem down.

I then tried re-learning UP/DOWN on the remote, and kept LEFT/RIGHT as the original to see if the actual IR-codes had anything to do with the initial delay problem.

It definitely seems so.

UP/DOWN got a bit faster response-time. It does make a difference. HOWEVER, it got considerable longer inter-key delay just as if the delay was actually inside the ir-code at the end. Meaning it started buffering them again.

So it seems the new ir-codes had less initial delay problem but a lot more inter-key delay problem. With this information maybe someone has experience with this type of problem?

/D