the mantra around here is that "avidemux is not a video player."
I am agree with you in 100%. But it's retarding almost to half speed, ie to see one hour of video I need two real-time ones. It's so uncomfortable

Check if there is update for video card driver?
I have laptop with CPU - Mobile DualCore AMD Athlon 64 X2 TK-55, 1800 MHz; motherboard - MCP67M nVIDIA nForce 610M, with integrated NVIDIA GeForce 7000M (it does't support any hw accel., and it's so old).
So, there is not (and will be not) any driver updates to my videocard. However, the conversation is about CPU, and it's cores. Video card is not to blame.
ps Seems like I have to change my laptop to something modern...