Restricted performance

Morning all.
Looking for some advise on a restricted performance warning that I'm encountering on my 2011 RRS.
I've not owned the car long but have had the amber restricted performance warning twice under the exact same circumstance i.e. on a 220 mile journey after stopping for a coffee around half way and warning appears on start up. It disappears the following morning and I didn't think there was any loss of performance until I noticed last night that while driving in cruise control at 70 mph the speed dropped to approximately 55 mph on a hill. The speed slowly recovered but I have not been able to test what happens under similar conditions without the restricted performance warning as I'm now heading offshore for few weeks.
No other warnings appear with the amber light but can anyone shed any light on why this would only manifest itself on restart after a 100 miles driving and would the cruise power loss be related?
Thanks in advance for any suggestions and please be aware thwre will be delays in my response due to work / shifts.

Could be all sorts of things. Have you got diagnostics of any kind. Should log a fault or pending fault with any luck.

How many miles has the car done? What engine? Has gearbox oil ever been changed?

The mileage is 74k and it's the 3.0 diesel. Not sure about the transmission oil but would say probably not. I've not invested in a diagnostic tool yet but will in the near future - the dealer checked for fault code after the first episode but nothing was stored.

Temperature rise occurring when you stop is a possible cause. Check the radiator is clear and also the gearbox oil cooler.

Datatek said:

Temperature rise occurring when you stop is a possible cause. Check the radiator is clear and also the gearbox oil cooler.

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Unfortunately (stupidly more like) I have omitted to mention that the same warning did come on one morning on initial start up but after a very short journey and then left for a couple of hours it had cleared. Apologies for this ommision which has obviously confused matters further but in a 3 week period those are the only 3 occurrences. I did think the problem would be heat related but the early morning appearance might dispel this

Whittonblue said:

Unfortunately (stupidly more like) I have omitted to mention that the same warning did come on one morning on initial start up but after a very short journey and then left for a couple of hours it had cleared. Apologies for this ommision which has obviously confused matters further but in a 3 week period those are the only 3 occurrences. I did think the problem would be heat related but the early morning appearance might dispel this

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You might like to check the battery and the charging voltage.