Get a small tire bike, your 5'8" you should look into either single speed frame mini velo and build it into a IGH 3 speed.
I ride folding bikes that I beef up, so that I can ride them daily.
Being less then 6' tall is a blessing not a curse, when it comes to bikes these days because your in the size rage for a small tire bike.
I ride a itzy breezer; That has been custom-ed to fit 16 inch wheels but only allows for a 50T front sprocket,(winter bike) and a xidesheng small flyer 16 inch folder, 60 tooth front sprocket and a 13t sturmey archer AW 3 speed, IGH only for me.You might think its not fast because of the wheels size but it is very fast, I can ride faster then most road bikes carbon fiber included. That's all I will say without sounding egotistical.
If you want comfort you can get a seat post with a shock and possibly a front shock fork. I don't bother with shocks at all,
If you want speed you leave shocks alone,
I can ride 40 miles like nothing on mine if I want to go fast the whole way it
drains me some, but not too bad. 2 hours and 20 minutes for 40 miles with hills and rough roads and stop lights included.
keeping the weight under about 22 pounds will help but not a major deal, because the small tires will give you more ease of motion to allow for extra weight which won't be noticed as much.
I use Kenda west 16 x 1.50 100 psi. zoom zoom. Note( sturmey archer defaults in 3rd gear shimano 3 speed defalts in 1st gear)
Good luck.