I found out this game has a memory leak issue on Arch Linux XFCE Desktop, on Linux and Browser version. This is easy to replicate by opening and closing the menu multiple times. Each time you open the menu ram usage will increase and if done enough, your machine can get overloaded. I think the android version also has this issue, I haven't tried it but I had played other rpg maker games on android that also get slow whenever you open the menu.
I recommend restarting the game whenever you feel it getting slower. On PC, have a task manager open to monitor ram usage. I didn't notice the game getting slower on my machine before it got overloaded.
This issue is fairly common with rpg maker games. I also tried the Windows version with Wine (it translates Windows2Linux) and it also has that bug, but ram only increases by a few mbs so it's usually not a problem and it's very unnoticeable. I don't know if this is a problem when you run this on Windows.
Your newer games like Dampftraun don't have this issue though, so that's good ^^