I had the exact same dilemma as you, Pie. Stuck in a slower gear. I noticed, watching YT videos, that most amateurs are stuck in the same slow to moderate gear. I, and they, even choose slower songs to learn...songs that match my/their slow natural pace. I'd say "I wish I could play like Kalei Gamiao", then I'd pick Hotel California to learn (a great song, played superbly and intricately by some...just not a speedy song). Huh? How will I ever play like Kalei, or Jake, or Taimane, if I don't start to emulate them?
So I broke with all conventional wisdom about a year ago and pushed my pace. I threw out all advice to slowly work through bits for the purpose of muscle memory and all that jazz. Precision? Who cares...it'll come. At first, I took little snippets that I already knew well and I pushed the tempo. Sloppy, sure, but I was astonished to find that, in short order, I could play it faster. Much faster! And precision at higher tempo came quicker than I thought, in a matter of a couple weeks by playing it for maybe thirty minutes a day. I started taking slower songs that I knew well and pushed them abnormally fast just for fun. Wow!
Then I applied this principle to new songs for me. I first tried Jake Shim Kelly's Song 143, a moderately fast song, and learned it anew, took a little time to memorize the fingering (it's relatively easy fingering, but sounds lush and powerful). Still sloppy, though, at slow speeds, I pushed the tempo to play it more like Jake. Learn it well while simultaneously pushing the pace, I told myself. Bam! I made more gains than I would have with the old "keep going slow until its precise, then later push the pace" (which typically translates to: learn it slowly until I get sick of it and then move to another song before I ever get it to proper tempo...lol).
https://m.youtube.com/watch?v=PZBK2dEbRTs
Bonus to pace pushing: I had a ton more fun in the process! I'm much more confident with faster numbers now. Learning Kalei's Mach 4 at the moment. Can I play it slowly and precisely yet? No. Am I pushing the tempo yet? Yes!
Just my personal experience. What has worked for me to take me out of a moderately slow speed rut. Maybe it can work for you, Pie. Cheers.