1- I played windows version and experienced no lag at all on my MSI laptop.
2- My first thought was that I realllyyyy love the soundtrack for it, i love that I can change her name, It took me a moment to get into the flow but when I did I became really intrigued and wanted to know more.
3- I like the heatwave animation, it adds an atmosphere to the story and gives it that real life hazy feel, and since she has repeated this summer a thousand times it makes sense to have that haziness. I also like how you've done the character animations, it helps to engage players that much more into their world.
4- The writing is enjoyable, it suits how you've portrayed the characters and flows nicely.
5- Hmm, maybe having the timer a little longer, just a smidge because when it came up I wasn't prepared (like in real life I suppose haha) and I didn't really have time to read it, I just froze and let it run out... ^^;
6- My absolute favourite thing is the music especially the title music, and I love the error type animation of the first scene where you name rin. I like the colour silhouettes for the characters.
Overall I can't wait for the full version! :D I'm excited to see where you take this and good luck :)