Hi...
It's a shame you didn't ask before making hardware purchases as the RX570 was maybe not a good purchase for Character Creator. It's only a budget graphics card with low onboard video ram.
A much better choice would have been a Nvidia GTX 1070, 1080 with 8GB of video ram or if your budget allowed an RTX 2070 or 2080.
That said you should be able to improve performance on your current setup by making sure you have latest graphics drivers installed and also ensure that you don't have any other applications running when using Character Creator. It will also be worth going into your CC3 Preferences (CTRL+P) and reduce the "Max Texture Size" to say 2048 x 2048 and see if this helps. Also if the problems continue you can consider lowering your overall visual quality by changing the Real-time Render Options > Quality dropdown to Medium or lower.
Hopefully this will help.
:)
Peter
Forum Administrator
www.reallusion.com