HP Vectra XW Optimization Manual page 16

One single-threaded application
Multiple single-threaded applications or one multithreaded application
NOTE
1 Your Personal Workstation's Performance Features
Advantages of Dual Processor Configurations
This distinction is important. If you use multithreaded applications or
multiple single-threaded applications, a second Pentium Pro processor
will significantly improve the performance of your system. If, however,
you run just one single-threaded application, then the second processor
will offer little, or no performance advantage.
10 English
O/S 1 and O/S 2
are multithreaded
operating system
functions
AP 1 and AP 2
are application
functions