2nd post of today - its too early to be typing!

My 55 plate E60 M5 was bought only 6 months ago, from one prev owner and full service history, which seems to have been well cared for. However, my idrive is extremely slow, and at times i can wait 10-15 seconds for any response when i play with the drive knob. Is this common on this age of E60 and can it easily be sorted? I have a comprehensive warranty but with a £100 excess, so I want to avoid booking it in. I hoped that the system perhaps could be reset? I refer to my other thread which asks for help with a parking sensor failure problem. Thank you.