Hybrid Bicycles - Does more PSI in a Tire mean Quicker movement?

I have a Trek 7.3 FX and a few weeks ago I took a spill and the bike shop had to replace my rear tire. Instead of placing the same Bontrager Race Lite Hardcase (110 psi) where my front tire is, they placed a Continental Contact (85 psi) on the rear tire. Is there a difference in speed when there are 2 different tires with 2 different PSI's? This would not really bother me that much, but from time to time, I compete in 5/10K road races, so I was just wondering if it changes my speed with my bike or if it doesn't really matter that much. Thanks!

I am not an expert but the common knowledge is this, narrower tires with higher psi will give more speed due to less contact to the surface,wider and lower tire with less psi give smoother comfy ride but speed will decrease.I don't think that's a good idea you are about to do to the swap.

It strikes me as odd that you compete in roadraces, yet you do not know that more pressure and thinner tyres will give you less rolling resistance.
Nevertheless ... as kungpaoschwinn stated: more pressure will also give you a less comfortable ride ... so don't overdo it either ;)

Thanks KungPao! That helps and yeah Adelaa, I only compete in a 5/10K road race once a year and in the type of competition I ride in athletes can use any bike, so I'm not really that experienced in the whole tire thing and knowing what kind of tires I need and all. I've been using the the same tires (its been replaced once since I got the bike) on my Trek FX 7.3, so I don't know much about it. Thanks for your help though too!