Hi there,
There are a few solutions on AskF5 which detail this:
SOL3242: Traffic Management Microkernel (TMM) CPU and RAM usage
https://support.f5.com/kb/en-us/solutions/public/3000/200/sol3242.html ([url]https://support.f5.com/kb/en-us/solutions/public/3000/200/sol3242.html[/url])
SOL3572: CPU usage is significantly higher after upgrading to BIG-IP version 9.0 or later
https://support.f5.com/kb/en-us/solutions/public/3000/500/sol3572.html ([url]https://support.f5.com/kb/en-us/solutions/public/3000/500/sol3572.html[/url])
Reply if you have any questions on this info.
Aaron