Thanks @AdamM for your answer. We have also used the nproc limits, but it creates a lot of 503 errors and the clients become disappointed with the performance. We host multitude of clients with lots of different systems other than WordPress so can't activate caching for their apps.
So as per your saying, we can mitigate it if the settings are saved correctly?
This needs to be done on priority then as it will cause us more harm in terms of client dissatisfaction than benefit.