Low FPS on Mojave 10.14.5

FPS issues in Mojave.
In macOS High Sierra 10.13.6 I usually get 70-125 fps on medium setting at 1440p 144Hz monitor. Its playable, no lagging and for the most part smooth.

I decided today, since I have a 3 day weekend to install Mojave on a second ssd drive as I did not want to risk screwing up my current HS disk. So I did a fresh install on Mojave on a brand new Crucial SSD, installed BattleNet and SC2. This is the only thing currently installed so far.

In game, set graphics just like I have it set in HS, launched and was shocked at the fps. I was only getting 60 on start and by the time I had 60 units I was at 22 fps. In battle it is horrible.

I made sure all a accessibility settings were right, restarted several times to no avail.

Temps are fine, video card never hits above 65c, both cpus hover around 55c in game. I am at a loss. I switch back to HS and everything works fine.

I have even went so far as to remove every drive minus boot drive

System specs:
5,1 Mac Pro
2 x X5677 8c/16t 3.46GHz dual Xeons (3.8Ghz boost)
AMD Radeon RX 580 8GB
32 GB 1333 ECC Ram
500GB SSD (High Sierra installation)
500GB SSD (Mojave installation)
2x WD 1TB Black Data drives.

For testing, I have tried a Vega 56, and a RX 470 as well. Funny thing, they all get the same fps except the Vega 56, its a smidge more but not much.

Any ideas?
Also, is there any update on the Metal API being finalized on the horizon?

Did a test in Geekbench between the 2 OSes using the lowest video card. Radeon RX 470:

Geekbench test results:
CPU Test
Single Core 2982
Multi Core 18904
High Sierra
Single Core 3051
Multi Core 17452

Compute (Graphics Score)
High Sierra 119072
Mojave 118194

I will test the RX 580 and Vega 56 tomorrow, I will also add Unigen test scores to see if they are similar.

Edit 6.15.2019
Ok so I tested the Rx580 and Vega 56 today. Results below.

RX 580
CPU Test
Mojave SC 3096 MC 18953
High Sierra SC 3076 MC 17628

Compute (Graphics Score)
High Sierra 140065
Mojave 134692

Vega 56
CPU Test
Mojave SC 3009 MC 18792
High Sierra SC 3021 MC 17946

Compute (Graphics Score)
High Sierra 219741
Mojave 219828

I also played WoW, with the RX580 and on preset 7 was averaging 75-120 in 5 mans and questing. With a lot of spells flying it dropped to the 60s but nothing dramatic that is not normal. This was in Mojave. I had similar results in High Sierra.

I do notice with the fps counter up (ctrl+alt+f) in SC2 in Mojave it hovers at 72fps all the time in the beginning until more units are being deployed, then drops into the 20s. I can not duplicate this issue in High Sierra. In HS It starts at my refresh rate of 144 and as I build more units and even in fights it only drops to a low of mid 60s. I doubled checked all the settings, made sure all settings were identical and no I did not use the fps limiter commands.

2 weeks and no replies from Blizz. I have given every bit of pertinent information. Why no replies Blizz?

Nothing …

@Loadedaxe, did you ever find a resolution to this issue?