Today, I have a good method for low end PCs like me, specially for "Intel" users. The method is just changing the resolution.
Intel users:
Right click on your desktop and click on "Intel Graphics Settings"
(https://preview.ibb.co/iKy6je/Screenshot_163.png)
Click on Display
(https://preview.ibb.co/nmxcqK/Screenshot_164.png)
Click on "Maintain Display Scaling".
(https://preview.ibb.co/gJBLAK/Screenshot_165.png)
This should fix the black bars on the side
Now head ingame, and change the resolution to 800x600
You will notice a huge FPS boost (Probably 10+ FPS).
Here are 2 pictures, both with same settings. One with 800x600 resolution, another with 1280x720 resolution.
1280x720 Resolution: 25 FPS
(https://preview.ibb.co/jJZbHz/Screenshot_162.png)
800x600 Resolution:
(https://preview.ibb.co/fJWHPe/Screenshot_161.png)
Chat will be too big, so I suggest you change it to 18 or 17.
My specs:
Intel core i5-6300U
8GB RAM
Intel HD 520
I hope this method satisfy most Intel users. :)