Uncompressed YV12, (Avisynth/ffmsindex/VirtualDubMod/Direct Stream Copy), 4 min 14 sec, CPU 65%, 20572MB MagicYUV, (no mulltithreading, enabling it slowed encoding speed by 2 or 3 fps), 4 min 23 sec, CPU 97%, 5823MB Lagarith, (no mulltithreading, enabling it slowed encoding speed by 2 or 3 fps), 4 min 7 sec, CPU 90%, 5451MB Huffyuv (ffdshow variant, adaptive huffman tables enabled), 4 min 1 sec, CPU 80%, 5897MB Huffyuv (ffdshow variant), 4 min 23 sec, CPU 85%, 9542MB Encoding the first 15 to 30 seconds indicated multithreaded mode was slower for both Lagarith and MagicYUV so I disabled it. Output written to the first partition of a RAID-0 volume to take hard drive speed out the equation as much as possible. Uncompressed RGB, 30 seconds, CPU 45%, 4.3GBДҐ minute, 1920x1040 MKV with Avisynth/ffmsindex/VirtualDub (fast recompress). Uncompressed YV12 (Avisynth script/Direct Stream Copy), 15 seconds, CPU 45%, 2.1GB copying the largest file (990.8MB) from the location of the source file to the same location as the output files took around 6 seconds. MagicYUV, 17/12 seconds, CPU 60%/83%, 586.8MBДЇor a hard drive speed reference. Huffyuv (ffdshow variant, adaptive huffman tables enabled), 16 seconds, CPU 62%, 587.2MB Huffyuv (ffdshow variant), 16 seconds, CPU 62%, 990.8MB CPU usage is a fairly rough average anyway. Without and with multi-threading enabled. For Lagarith and MagicYUV there's two time and CPU usage figures.

Total time as displayed by VirtualDubMod. Recompressing a 3min, 49sec 704x384 AVI with VirtualDubMod (fast recompress).

Virtualdub fast recompress