It may also depend on which connection mode you’re using. The legacy option has the browser download the assets from the server and then send them to the companion. The new connection mode based on WebRTC sends the names of the files to the companion, which then downloads them directly (bypassing the browser). In the former case, browsers that are better at optimizing memory use will likely appear faster than those that don’t optimize memory well. Any browser extensions, as well as antivirus software that might be scanning any files loaded by the browser, may also interfere.