I have been playing on a laptop in the beginning.
It wasn't very easy to play it , the FPS dropped becouse of several reasons.
-> Bad Processor (i3 intel core)
-> Low RAM (2 -> 4 GB)
If you are playing on a laptop and you have FPS problems , your hardware might be the issue.
It is hard to find a laptop with good hardware without paying too much. A laptop costs a lot more then a desktop.
The main requirements for gaming are a good processor and decent RAM.
Make sure your hardware is decent.
In case you have good hardware & still experience FPS lag , you have to do some changes in your setting. Try to play on a lower resolution & make sure special effects (Shadows for example) arent on , it will make your FPS higher!
Playing games on a desktop is the best thing to do , it is cheaper then playing on a laptop , you can buy a cheap computer with good peaces.
Just make sure you have these things in it :
-> i5 intelcore processer (i7 is even better!)
-> 8 GB RAM at least for smooth gameplay.
One thing is really important to know , If you are having FPS lags , it is because of your hardware , not because of the game or the servers!
Pinglags are another issue offcourse...
So my tips for fixing FPS lag
1) Lower resolution & graphics
2) Upgrade your RAM
3) Make sure you have a good processor