Here is a chart that compares Lumia Nokia 610, Nokia 800 and Nokia Lumia Lumia 900. We analyze the new Nokia Lumia 610, of which many are calling for the differences in performance due to less RAM memory.
As the first point the developers of Nokia have been analyzing the rendering of video playback and found that, although supported, but putting a video encoded in an unsupported codec with hardware acceleration, bitrate or higher resolution compared to the baseline Windows Phone, the software may be unable to play the file correctly.
"Video in a supported format but encoded in a codec not supported with hardware acceleration or at higher bitrates or resolutions than the Windows Phone baseline, may either fail to playback or be rendered in software. If software rendering occurs playback will be poor — jumpy and choppy.For example, a video using the VC1 codec Advanced or Main profiles may play through software rendering, instead of hardware acceleration, but if the encoded bitrate is too high it will fail.7x27a-powered phones impose limitations on the video they can play.
These limitations have been implemented to account for the lower processing capacity and memory of these phones. However, by re-encoding your video and making use of the techniques outlined in this article you can preserve your apps UX and continue to offer your users a rich video experience."