You can have more than one browser on any computer. You can download Chrome and have blazing fast BYC and still use your old browser to do your work. They aren't mutually exclusive!
Also, a TON of thought went into the hardware and browsers folks use. Lots of testing, too. It's unfortunate, but at some point, staying with old stuff causes lots of instability, and just because it wasn't visible to BYCers doesn't mean it wouldn't affect or crash the site in the future, as the internet evolved around an archaic platform.
Change is difficult, but in small bites, it can be doable. I encourage everyone to download Chrome, even if it's just to use for BYC, then as you get used to it, you can transition over. It's not at all advisable to leave your old browser alone and not update it- in fact, you may have drag associated with malware running in the background, as that is the first symptom of an old browser being in use: infection.
C'mon folks! We can do this! It's a fine change and you'll enjoy the new BYC more if you open up a little to the big improvements and don't focus on the changes being negative!