User concurrency and neo4j CPU core

Hi Team,

I work on an application that uses neo4j 4.4.19. The db has around 20 lakhs + nodes.
we have 2 read neo4j node and one write (leader) node
say,
core0(read) - (with a CPU 2 core)
core1(read) - (with a CPU 2 core)
core2(leader/write) - (with a CPU 2 core)
in total of 6 CPU

During the performance testing , the team would stress the application with high number of concurrent users, like around 100 users using the application in 1 hour of time. In those cases we could see large response times and the CPU utilization of read servers core0 and core1 are always 100% throughout the test.

Please suggest in these cases, what's the ideal CPU to be allotted for instances.
Also please suggest an ideal infra setup for such case.

@michael.hunger could you please help here