Thanks for enjoying it.
First time I heard of slowdowns in the web version. Probably because of the file size? Hm.
You didn't have to download it from the other source. You can download it right here, for free :)
Viewing post in Agony Of The Healthy Sleep Final Day comments
Ah right I just thought it would be the same version as the one itch downloaded ^^;
and since it was the itch version that had the slowdown for me I thought it was better to check and external source instead which worked for me in this case ^^
Also I used the Desktop app for itch :) might be the reason for the slowdowns.
:EDIT: Just tried the web version of the game and no slowdowns or freezes occurs... so that seems it is only the automatic version the desktop app downloads that is the problem it seems ... at least for me :)