slow hybrid bike 700cx35c
I second @SteveLoughran's advice to try skinnier tires (tyres), but maybe you also need more training.  Personally I'm either older, fatter, or both compared to the people in my weekly riding group, and I've always just been plain slow; I already have a road bike with skinny tires, so my only remedy is to put in the kilometers.  If I read your post correctly you're riding distances of 30 km, which isn't all that far.  If you do some longer training rides, of say 50 km, then 30 km will seem considerably easier.

Also consider interval training, which is a great way to get faster.  The basic idea is to go flat-out for short intervals during a normal training ride, with easy effort intervals in between to recover.  Perhaps three periods of maximum effort for three minutes each, with three-minute recovery intervals in between.  Articles about interval training abound on the web.  Intervals hurt, but they work.

Lastly, if you're lugging a few extra kilograms, it can't hurt to lose some.