Sorry, but a FPS rate spanning from 300 to 500 is anything but stable. If your monthly paycheck was changing like this, would you consider your wage to be stable? I guess not.
However, you may always want to cap the refresh rate at a value that your system will manage to maintain at 99% of the time. There's absolutely no reason to melt down your system for FPS boosts a human brain probably can't even recognize. Just try raising the maxfps by steps of 10 starting at 60 and stop where you are no more realizing any differences to the rate you had before. Then you may even have some CPU/GPU resources left to change some graphic settings from horrible (seriously, why even play such a game then?) to moderate or even high.
For instance set /maxfps to 120. Now you'll have indeed a stable FPS rate and the game might run smoother already. Those occasional FPS drops are more likely CPU bound, therefore your graphics card may have nothing to do with this. A truely stable FPS rate which doesn't max out on the CPU can prevent such drops in performance.
Hope that helps.
However, you may always want to cap the refresh rate at a value that your system will manage to maintain at 99% of the time. There's absolutely no reason to melt down your system for FPS boosts a human brain probably can't even recognize. Just try raising the maxfps by steps of 10 starting at 60 and stop where you are no more realizing any differences to the rate you had before. Then you may even have some CPU/GPU resources left to change some graphic settings from horrible (seriously, why even play such a game then?) to moderate or even high.
For instance set /maxfps to 120. Now you'll have indeed a stable FPS rate and the game might run smoother already. Those occasional FPS drops are more likely CPU bound, therefore your graphics card may have nothing to do with this. A truely stable FPS rate which doesn't max out on the CPU can prevent such drops in performance.
Hope that helps.