One of the conditions which contributed to the high speed of this event is that two smaller CMEs were launched a little earlier, and these events cleared out much of the solar wind material, leaving little to slow the outflow of the July 23 event (UTC).
In the visualizations below, generated from the Enlil space weather model, green represents particle density, usually protons and other ions. In green, we see the Parker spiral moving out from the sun generated by the sun's current sheet (Wikipedia). Red represents particles at high temperatures and shows the CME is hotter than the usual solar wind flow. Large changes in density are represented in blue. These three colors sometimes combine to tell us more about the characteristics of the event (noted in the 3-color Venn diagram below).
However, if this CME had struck Earth's magnetosphere, which has a much stronger magnetic field, the changing magnetic field would induce much larger voltages in systems with long electrical conductors, such as power lines that run over long distances. These significantly higher voltages can damage power transformers.