Thanks for your feedback! Fantastic list of feedback, we've not had a whole lot of time to playtest, so its very welcome!
We're aware that the browser perf is bad, which was a bit unexpected since the PC build performance was great, so we'll have a look at that as well.
For most of the other issues we've already have done work as well, actually had a lot of features turned off for our submission as they werent complete, including the switching between LMB and RMB for controls/selecting.
Thanks for giving our game a try, we'll post another update soon!