It depends on outside air temperature. If the outside air is at 100 plus, and recirculation is NOT on, the AC must cool 100 degree air down to a livable temperature. If recirculation is on, it uses the already cooler air in the cabin for the intake of the AC which makes the cabin temperature a bit lower. All bets are off if you have windows open (you are back to cooling outside air again).
If the outside air is already cooler (such as 80 degrees), the benefit of recirculation is smaller.
Storm titanium 2005 Elise with carbon fiber spoiler, BWR sway bar, BOE toe links, gPan2, LidBone, sector 111 wheel studs, Grey RAC Monolite wheels with toyo R1R, Team Dynamics 1.4 with Hoosier A6/R6s, Katana2 Supercharger, ECU with 265 flash. PPE headers w/decat, CEL angle eliminator, Silent touch catback, Rear Panel Eliminator, HKS intake, V2 fuel tank, Walbro255 fuel pump. HID lights.