If you have problem with the hairstyles please try the following suggestions:

1. Turn Sim Quality setting higher.
2. If the textures are blurry or have compression artifacts, enable Uncompressed Sim Textures option.
3. Turn Lighting Quality to higher setting for shiny hair issue.
4. Update the game (patch may update game files structure, meaning hair that were made with newer version might not work with older version of the game).
5. If the above doesn't help - Turn off Laptop Mode (may affects performance and hardware heat).

Additional tips to help with the performance and hardware heat.

1. Turn on VSync (Vertical Sync) to help prevent overheating by avoid drawing frames exceeding your monitor's refresh rate.

1.1. If VSync doesn't work well or introduce stutter:

Go to "Documents\Electronic Arts\The Sims 4" and open Options.ini with Notepad, find "frameratelimit" and set it accordingly to your display's refresh rate (i.e. 60).

2. Turn off Reflection (affects mirrors and water).

3. Turn off Edge Smoothing or use lower setting like 2x (Anti-Aliasing).