Its only a little thing but it does usually speed things up, if only by a little.
XPhome or proffesional assigns priorities to the procceses it runs and by default your procceses will run as "normal". If you up the prority for Lomac to "high" you make sure that Lomac gets as much attention from the OS as possible. This will not make any giant increase in performance but it might give you a frame or two when you most need it.
How to:
1: Right-click on the shortcut for lomac and choose "properties"
2:in the target line write:
C:\WINDOWS\system32\cmd.exe /c start "runhigh" /high "C:\Program Files\Ubisoft\Eagle Dynamics\Lock On\LockOn.exe
Note!: if you have installed either Lomac or winXP to a different directory than i, remember to change the targetline accordingly