Veejay's performance depends much on the memory bandwith, CPU and disk access.
Has a live performance tools, veejay experience have to be reactive. You can achieve that finding the right balance between your hardware capacities, the video resolution, the complexity of the effects chain.
For HDTV (1280x720) resolution with mjpeg codec, you need at least a 2.5 ghz. The faster the better.
For full PAL / NTSC resolutions (720x576 resp. 720x480), DV / Mjpeg you need at least a 1.5 ghz, for lower resolution (352x288) you can do fine with a 500-800 mhz PC.
Your best bet is working in RAW or MLZO (compressed) YUV 4:2:0 / 4:2:2. On my pentium 4 , 3.0 ghz playing a AVI file that contains RAW YUV frames
uses about 3-4% for a full PAL movie and 10-12% for mixing 2 movies.
The tradeoff here is your diskspeed. You could use compression, this reduces the size of the videofile anywhere between 0-30% .
Typical for laptops is slow disk speed access, using a SSD device storage is a good option.
You can test your hard drive with $ hdparm -T -t /dev/hdX
If you need to record without framedrop, you can do so by disabling audio and
disabling synchronization with the command line options -a0 -c0.