H.264 codecs are pretty CPU intensive and VLC can’t use multi-cores to decode it yet.
So if your computer is dying when decoding 1080p samples from H264, do the following.

Open the preferences
Tick advanced in the lower right corner
Go to “Input/Codec”
Go to “other codecs” subcategory
Go to “FFmpeg”
Put the “skip-filter for H264″ to all
Restart VLC