Hi ldd. You mentioned the engine cooling fan. The moment you hear the fan coming on, try hitting the Off switch for the ventilation/heater. Does the engine fan sound (maybe aircon) cut out immediately too?
I have just bought a 2012 ES and noticed the engine fan or air-conditioning coming on in frequent short bursts, even in cold weather and with the (auto) air-conditioning off.
I eventually tried the ventilation on/off switch. Each time I switch the heater/ventilation fan back on, even at its slowest, the short bursts of "engine" fan resume. It appears to be linked to the air-conditioning. Dealer's turn next, unless anyone recognises this?
Since I've only had the car a couple of weeks I can't tell if the performance is down a fraction, but the engine does run smoothly. Using the air-conditioning usually leads to small power loss, it might explain your sensation and a drop in fuel consumption.