From what i read and im not expert this is only for applications with coding needs to be run every Xms (below the normal rate) I dont think this would really have any impact on performance (increasing it).
TimerResolution is an application to change the resolution of the default windows timer. The standard timer on Windows XP can vary between 10 and 25 milliseconds. Therefore if your code uses a timer or sleep value less than the timer resolution on your system you won’t be getting the results you expect.
The timer resolution will be globally changed while the application is running and will revert to the previous value when it is closed.
Seems rather pointless, wether or not it will increase CPU usage a little I dont know. Considering I have never heard of any others gamers talking about this I dont think it amount to anything.