four factors limit a bike's "speed".. rolling resistance... wind resistance.... acceleration of weight involved... and the rider's ability to generate torque.

you partially addressed rolling resistance. Higher tire pressures and narrower tires will reduce resistance, but also reduce comfort and versatility....

you are sitting too upright for serious speed without a big downhill or strong tailwind being needed... and the other two factors mostly involve you, which we have only one specific bit of info about.

does your bike have suspension?? That Slows you down by eating up Energy, and ADDS 3 to 7 Lbs. of weight to the bike. Steel Bars? Extra Weight... etc...

are you using toe clips or shoes/cleats? this will help you to pedal more efficiently.
bigger gearing only helps if you're running out of foot speed on flat ground. Foot bounce from not being clipped to the pedals slows top speed quite a bit too...

riding more helps you lose weight, and makes you a stronger rider... there's only one way to do that.
go ride... and think of the hills as a challenge, not a problem to be avoided.

is this like your bike? not seeing an "OutlandER" anywhere...
https://mtbdatabase.com/bikes/2021/f...utland-29-1-1/

that's an entry level DH bike. are you doing lots of jumping and stunts?
it was never intended to go fast on pavement, or on level ground, for that matter.
some might opt for up to a 36 tooth chainring, but not much more... you'll need a longer chain if you swap out to a larger ring from the stock 32.

best advice? get a different bike.... i'd advise a cross country(with lockout susp.), gravel or cx bike for you.




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