Performance Fraction (PF)
From FaHWiki
The Performance Fraction of the Folding@Home client is the value "calculated by the client as a benchmark of the system's ability to complete work units quickly. It is a sliding window average of the fraction of the deadline time remaining when a unit is completed, weighted over the recorded number of units. The number of units is capped at four, exactly as it is for the network download and upload rates."
A simplified calculation of the PF would look something like this:
PF - Performance Fraction of the just completed WU
UPF - Updated Performance Fraction
UPF=((4*UPF)+PF)/5
In practical terms, it's sort of like this: The performance fraction is the average amount of time remaining to the deadline that the last four units have completed with. So for instance if you finished the last four units using only 5% of the time to the deadline your PF would be 0.950000, and if you took 90% of the time to the deadline your PF would be 0.100000. The higher the PF the better.
Since v6 client code base PF is no longer used and removed from the Server Status page, because it didn't work as expected. Instead, a lot of preformance parameters of the machine is taken into consideration and the resulting performance is used for choosing optimal WU for the client.
