Is somebody experiencing the same thing?
My fan spins like crazy when I do a long and loaded-effects project. Unfortunately I am not able to understand what to tweak or change to solve this issue. Sometimes I am afraid that I'll break my machine if I don't find a solution. In the screenshot I uploaded, you can see what how much power AME is taking in monitor activity if that can help. Also I wrote my machine specs.
Model Identifier: iMac13,1
Processor Name: Intel Core i7
Processor Speed: 3.1GHz
Number of Processors: 1
Total Number of Cores: 4
Memory: 16 GB
Graphics: NVIDIA GeFroce GT 650M 512 MB
Overheating is usually a hardware issue, not a software issue. Make sure your fans and machine are completely free of dust and have proper ventilation. If your machine does crash during an export due to overheating, you may need a new fan or other hardware.
Having said that, the only way to limit resource usage with Adobe apps is the memory usage, by going into Edit > Preferences > Memory. If you find a render slowing down other apps so you can't use them, increase the "RAM reserved for other applications". This will of course slow down your render, but will leave more ram for other apps.
If CPU is what's maxing out and not RAM, then there's not a lot you can do other than upgrading your machine or buying a better GPU that is supported by Adobe CUDA Rendering, so you can switch your renderer to CUDA instead of Software Only which uses strictly the CPU. Since you're on an iMac, you only option is probably an eGPU (and don't upgrade to Mojave).