Will increasing the psi of my ac unit cause my energy bill to increase?

My energy bill has been outrageous lately and I'm trying to lower it. However, I was told that keeping my place at 78 degrees should lower it. The thing is that the ac doesn't catch up in the afternoon, so it gets really hot in my apartment. The other day I had a maintenance guy come buy and he adjusted the psi of the ac unit to 75 to help get the place colder. I'm wondering now that this has been done, will this cause my energy bill to increase even if I still keep the thermostat at 78 degrees in my apartment?