There are no security breaches, older versions just run faster for rotmg as it doesn't need any new features that have been implemented in newer projector versions.
How to download older flash projector versions:
The current link is:
Change the numbers to the desired version:
And open that link to download it. I'm currently using version 18, I'm not sure if older versions will help more with fps, but I've seen people use version 14 without problems.