Texture Loss can be extremely frustrating. I have 5 suggested steps to prevent it.
Step 1
Go into GTAV/lspdfr/lspdfr.ini & set Main.PreloadAllModels to false.
Step 2
Installing the Resource Adjuster.
Step 3
Removing high polygon vehicles. Anything above 200,000 may cause issues. To check this, open the vehicle .yft file and check the top left of your screen.
Step 4
Downgrade any 4K textures. If you're unsure, go back to the main menu & select Other.
Step 5
Lowering your texture quality within the GTAV settings.