Performance problems with ATL

[thelastsecret]

When I use ATL to make animations in Ren'Py all looks neat and all, but the CPU gets a full load which makes the fan of the laptop start. Not something you love to have during a quiet VN. This is always happening, even for fairly simple animations, e.g. a simple periodic glowing effect (alpha up and down) of one sprite or when a sprite slowly moves back and forth, so it's definitely not that this CPU load would be needed. (The problem does not occur, e.g., when I play full screen videos with Ren'Py!)
Anybody has any idea what's wrong there? And even better, how could I fix it?

I found this very old thread (so old that I didn't dare to reply there) which mentioned this problem, but came to no conclusion:
viewtopic.php?t=25698

About my laptop:
MacBook Air
2.2 GHz Intel Core i7
Graphics: Intel HD Graphics 6000 1536 MB

Thank you very much in advance!

[DarkChibiShadow]

I have problems with performance when any Snowblossom affect is on the screen and then movement is done with ATL at the same time (it causes a lot of visual lag) so I'm bumping this thread because I'm very curious to see what people have to say. Good luck!