perhaps also the fact that there is no graphics acceleration, the processor is solicited and avoids the shelving of certain application.
it's still odd that Safari is not concerned.
Someone has tested a Lion DP2 to see if the phenomenon was persistent about this version?

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Macmini early 2006 /blanGsak 10.7.2
Acer 8930 G / core2duo T6500 / NV 9600 GS m / Lion 10.7.3 / ML 10.8.2 / w7/8
Asus M5A97pro / FX 8350 / Asus HD 7950 CUII v2
GA-78LMT SP2 / FX 6100 / P x4 960t / Sapphire HD 4850 1024
MSI K9neo v1 / Atlon 4800+/ Gigabyte HD 5450 512
test kernel 12.0 AMD

Tuto : http://www.hack-my-mac.fr/index.php/...fx-buldo#28896

CG opérationnelle : HD 5450 512 / HD 4850 1 / GT 610