Is there an ideal air temperature for best performance in a light aircraft?
Good Evening Alex,
just for the record I'm a Private Pilot with about 150 hours of flight time, I would recommend speaking to a Flight instructor if you have any more questions about Aircraft POF. (principles of flight and performance) 

Best Performance can be narrow down to a simple formula  
Best Performance = High Pressure + Low Temperatures

1 hectopascal is equal to 30ft change 
1º celsius is equal to a 120ft change  br>

If you are looking for the landing and T/O I would suggest looking a Performance charts-which