I had the early cheap and nasty RM-L03 remote which while didn't have any problems responding to key presses started to have problems with the arrow keys sticking and trying to pull down the button next to them.
On the advice of this forum I contact Humax and I just needed to send in my receipt and 4 days later I had a nice and shiny RM-LM08 FOC. It’s a much higher quality remote and having the dedicated 'Recordings' button is a God send as it eliminates several key presses.
Response time of the remote seems great, but the box is still woefully slow in itself obviously though!