I use Chrome. Although I don't allow automatic updates I do check for updates once a week or so. I always update to the latest Flash and check it out on WGT. I've had no problems yet. The problem with Chrome Flash is the built-in Pepper Flash. You must disable this in plugins and then install ordinary Flash.
I also have an experimental version of Chrome called Canary. This, too, has Pepper Flash. Although it can be disabled it cannot be replaced because Adobe updates the default browser and Canary cannot be set to be the default as long as the stable version of Chrome is also installed.
Pepper Flash causes my hit to be at least two inches past the ding mark. This is a ball loser for sure.
Andyson has a really good computer and he can measure frame rate directly from Chrome. My Chrome will not allow that because I don't have hardware acceleration for my graphics. I found a way to fool Chrome to think that I did and tried to use the FPS tool that then appeared. Enabling this tool immediately kicked my idle CPU usage from 0-3 % to 29-31 % and delayed the hit to about an inch past the ding. Not too surprising since I was pulling a no-no. Needless to say, I undid that in a hurry.
Frankly, I'm tempted to buy a good graphics card, but so long as it's working, I probably won't. System is too old, anyway.
As an aside, I pay NO attention to all the hack notices I get in email, on Facebook, and such. They're 99.9% BS. If you have a question regarding them the first place to look is on SNOPES.