Yes, at any point where the CPU reaches maximum safe temperature, it will throttle, no matter if it is only being utilized by 5% or a 100%
It is throttling to prevent more heat generation, so actual load doesn mean anything with regards to when the CPU throttles - critically high temperature is what triggers it
I'm not saying neccessarily this is what happens, you'll need to identify possible thermal throttling, for example by monitoring a graph of CPU frequencies over a period of time (while gaming for example), to see if performce dips are present. If there are clear dips in frequency in relation to high temperatures, it is because the CPU is protecting itself from damage caused by excessive heat generation
But I must admit, that the very high operating temperatures you report seeing when gaming, is a very likely cause of the problems you experience, so to begin with, that the first issue I would try to fix.
If there are continued problems after returning CPU temperatures to an acceptable level, then it would be worth looking for other possible causes. But 90'c is quite hot, and will be able to cause damage to the CPU over time - so it should definately be adressed, in my opinion