I’m not trying to pass off blame to Kaspersky here, I apologize if I worded it poorly. What I’m trying to say is that you seem to have hit an obscure edge case where some combination of software/hardware on you computer (Browser? Extensions? Anti-Virus/Anti-Malware scanners? Flash player?) causes a catastrophic failure in the rendering of a Twitch stream page, and we need to first figure out what combination causes the failure (I assumed Kaspersky because you brought it up as a culprit) so that we can further debug it and find out WHY it happens.
JS files loading slowly should not lock up a browser, that behavior is fully expected and normal in a typical web browsing session. Likewise, it’s normal to rely on browser caching of files to speed up page load times, and the “new filename string” is a version number that changes when we update the contents of the file, so we can’t really optimize that.
Based on your report, every browser locks up when the flash player tries to load. What are the specs of your computer? What version of flash are you using? Are you running anti-virus/anti-malware other than kaspersky?
Again, “turn off your firewall” isn’t a permanent solution, it’s an attempt to find out what is causing the problem so that I can replicate it locally and fix it. “optimize your files to infinity” is not only extremely unlikely to happen, I’d also wager that it won’t solve your problem of flash crashing.