Rage Mp Client issue

[VENOMMKD]

Ok so a while back i started playing GTA V on the Rage Mp Client the issue that i encountered is while driving at high speeds with a car.My cpu was 100% and gpu at very low like 5% or 10%.The funny part is that i fixed the problem by using the scaling mode and put it in to 5/2 now the gpu is at 100% and the cpu around 75%.For sure its the Rage client because i get decent fps in GTA offline and there is 0 lag or sttutering even on high graphics options.My question is what can cause this wierd problem?

 

 

My specs:

Cpu: i5 6600k 3.5ghz quad oc

Gpu: Rx 580 8gb Armor 

Ram: 16gb hyper x

SSD: Samsung Evo 850