Hey there, I hope you don't mind, but I just uploaded a side-by-side video of this and the original 1987 Firebird release.
Viewing post in Bubble Bobble C64 Remastered comments
This isn’t my video, but the tempo slows down to normal between levels, and speeds up in game, and the gameplay feels faster than I remember it (tho I haven’t played the C64 version since I was a kid, so a little hard to tell). What I’m experiencing seems exactly like what’s in the video.
I’m playing in NTSC mode on the C64U. I haven’t been able to find any info confirming this game is supposed to be played in PAL or NTSC mode.
Edit: It does seem like normal if I do PAL. Would be nice to get a confirmation on the page that’s the intended mode, if that’s actually the case.