Hello, first of all, you need to have enabled hardware acceleration.
Here is how you can do it using Google Chrome
and here how to do it using Firefox
If you are not using any of two abose, you can find solution in Flash Player Settings.
To access the local Flash Player Settings Manager that is native to your operating system:
Windows: click Start > Settings > Control Panel > Flash Player
Macintosh: System Preferences (under Other) click Flash Player
Linux Gnome: System > Preferences > Adobe Flash Player
Linux KDE: System Settings > Adobe Flash Player
On Windows 10, you can simply search for "Flash Player"
Here are some more advices on how to make your graphics better.