Since FreeTrack overrides the priority command I've found a solution to this issue, even though I'm still wondering the reason of such override.
Without further ado here are the steps:
First of all we have to create a .cmd file into FreeTrack main folder (name it FreeTrack.cmd).
In it, using notepad (drag and drop onto it), write as following:
start FreeTrack.exe
ping 1.1.1.1 -n 1 -w 2000 > nul
wmic process where name="FreeTrack.exe" CALL setpriority 128
The ping part pings a fake IP once and then waits 2000 milliseconds (set a higher waiting time if this one doesn't work).
The third line changes the priority for all the processes under the name of "FreeTrack.exe" to, in this case, high.
Priorities:
Low: 64 Below Normal: 16384 Normal: 32 Above Normal: 32768 High: 128 Realtime: 256
If you don't like the command prompt window which appears for 2 seconds, create a .vbs file in the same folder of FreeTrack.cmd. This hides the cmd window.
Put the following into the .vbs file (edit with notepad):
Set WshShell = CreateObject("WScript.Shell" )
WshShell.Run chr(34) & "FreeTrack.cmd" & Chr(34), 0
Set WshShell = Nothing
Then create a shortcut on the desktop to the .vbs file and change the icon to the one of the executable.
However, I recommend the following FreeTrack alternative, which is more stable and doesn't need this hack:
Link 