My xbike kinda sucks

Hello friends,

I had a great time building up a 26" 90's steel mountain bike for a city/pub bike. Learned loads, enjoyed the research, and loved the whole process. Square taper cranks, 38t chain ring with Deore components, nitto drip, standard xbike fair!

The only thing is....it kinda sucks to ride. It's beautiful to look at, but it just feels like a chore peddling it around town. I know it won't be speedy, but it feels sluggish and a lot of effort to keep it at speed. I'm currently on 2.2" Holy Rollers which are pretty meaty and I'm sure aren't helping, but also nervous about dumping more money into it!

What do you think wise ones? What would you be thinking to make it more "fun" and a bit more zippy?