Radeon RX 580 Graphics

Hello all -

My old (2011) Mac mini died recently and I bought a new 2018 model that comes with Mojave and motherboard Intel UHD Graphics 630. Almost immediately I noticed the graphics were much slower when playing games, such as Call of Duty 2, than my previous 2011 model. FPS was less than half of what I was getting before and the disparity between me and other players' speed was much more pronounced. So I took the plunge and bought a Mercury Helios FX eGPU chassis from OtherWorld computing and an AMD Radeon Pulse RX 580 GPU card. I expected pronounced improvement with this combination.

Alas graphics performance with the new GPU was significantly WORSE that was I was getting with the built in graphics. FPS is almost half as slow as without the eGPU. CoD2 is almost unplayable at this point, all the other players are in fast motion like a cartoon. I did graphics optimization with the new card in the game before getting these results. Do graphic cards generally need extensive tweaking to get optimum performance? If so, how is that accomplished? Where would i find instructions for the same?

Any suggestions would be most appreciated. Thanks - Randy.