You can also change your hearthstone client to a custom resolution and FPS in a config file.
Go to C:\Users*YOUR USER HERE\AppData\Local\Blizzard\Hearthstone
Open options.txt
Insert following:
targetframerate:i=144 (number = desired framerate)
vsync:b=False
showfps:b=True (for a little number to show your fps, if desired)
My bot was running awful on low settings because it locks the fps to 30, then I increased the fps in the config file and it runned alot smoother.