2006 Kia Picanto Loss of acceleration

Smells problem
2006 Kia Picanto 40000 miles

Driving to work today (20miles, 15 of which is motorway) I was driving up the incline fron the M32 onto the M4. I noticed that the acceleration I usually have has gone I only reached 40 miles an hour by the time I leveled out and moved on to the motorway. Usually I can make 60 without pushing it. For the last 5 miles of my trip it ran at the usual 65, 70. Again was very slow to get there though. Also I had to switch off the aircon as there wasa nasty rubber burning smell.

Have I broke my car? What might be wrong?