Which codec ist the fastest to convert youtube videos?

[Joaho]

I have quite a collection of Youtube videos, all saved with VLC with the option "save raw data". Now my wife got a Toshiba TV with USB-port and wants to watch some of those.
The problem is, that the TV is playing many codecs indeed, but not the ones of raw youtube which is VP8 video and vorbis audio in flv container.

That means I have to convert them.
I tried with one video, converted it to H264/MP3. My notebook took one second for each two seconds of film and got quite into sweat.
The TV played that allright.

My question is: which codec combination is the fastest in conversion, without loosing too much quality?
Maybe somebody who knows the differences (I don´t) can give me a hint?

Thanks in advance!
Joaho

The TV accepts the following:
Video: Mpeg 1, 2, 4, H.263, H.264, VC1, AVS, MVC, Xvid, WMV3, Motion Jpeg
Audio: MPEG 1, 2, Layer 1/2/3, AAC/HEAAC, AC3/EAC3, LPCM/ADPCM, WMA
Ext.: all usual, including flv, but that not with VP8/vorb.