If you have an Nvidia GPU, changing your Textur Filtering settings may help increase performance.
- Right-click your desktop background and select NVIDIA Control Panel.
- Click Manage 3D settings on the left.
- Select the Program Settings Tab.
- Select Rocket League from the dropdown menu.
If Rocket League is not found, be sure to add it by clicking Add. - Change the Texture filter - Quality to High Performance.
- Find OpenGL Rendering GPU and select your GPU from the drop-down menu.
- Click Apply at the bottom.
If this did not help solve the issue try: How do I adjust Windows Power Mode to improve frame rate in Rocket League?