I tested your project on a Pixel 3 and got the following results:
C2: first switch ~232ms, later switches ~100ms
C3: first switch ~170ms, later switches ~100ms
So according to this, the C3 runtime is faster in this case. I don't know why other devices would be different, maybe specific hardware is better or worse in different cases.
Are you testing everything with high-end phones? We are trying to optimise our games for low end devices. Because everyone don't have good phones.
You can run this game smoothly with your device but other people can't, they don't have high-end phones.
I can say, I can't run this game too, so laggy with low CPU devices.
Construct 3 supports Android 5+ but you trying everything Android 9+.
Besides, C3 has a new feature that helps you hide this from the user - there's a built in memory management action "Load layout images", so you can load the next layout's images in the background while the current layout continues to run, and then switching layout will be instant. This feature is not available in C2. If I use "Load Layout 2 images in to memory" on start of layout in Layout 1, then it can switch layouts in around 5ms, which is far faster than you can ever achieve in C2.
I give a thanks to Toby R and rexrainbow . They are good developers. They made good addons for us (Game Developers). Which you don't like that ideas.
Try this Example (My 2nd example I was posted)
Just try one sprite and unload it from memory. That feature will not help you a lot. Because one sprite object using 1024x1024 png file. We can't edit, we can't move that sprites as a group. We don't have any access on spritesheeting. In this case Toby's MM Unloader plugin works better with C2. C3's memory features can't help you. It is all about spritesheeting, you know that. Also MM Preloader will help you load assets from another layouts, this will works perfectly because you can load with C2 what you want. C3 will load other assets from png file, which you can't unload.
Also people request good ideas, you was set status "declined"
So as far as I can tell C3 is both faster at loading layouts and it has a feature to help guarantee that layout switching will be instant, which works here.