In general, the viewer in the browser works very well as it does not consume the graphical resources of my notebook, nor does it heat up as it requires no effort, however, I noticed while walking and especially when I was running on some islands that my avatar had lag to continue running and It crashed a few times, I also noticed that on some islands, especially one I went to, it took much longer than normal to start loading the textures and objects and everything was grey, I think it took about 30 seconds to start loading. I don't know if this is a problem with SL in the browser or if it is a problem with the official viewer used. I hope they improve this.