Tell us your pc specs to see if it has enough power to play the game.

-Try to use another browser, eg chrome who has preinstalled flash player.
-Update you adobe flash player

If your pc is crap (like mine) you can try the old version as nikolgiorgos said as it is lighter.

Last solution could be to install an android emulator in your pc and play the android top11 version.
Emulator will consume resources (especially ram) but it will be much more stable than browser+flash