We also had the same problem. Cpu usage and number of connected clients (see dashboard) went up.
Software version: 188.8.131.52
We opened a case and advise was to disable HTTP/2 support. This solved our problem. All of them are stable again.
Comment from McAfee:
the issue could be a known Problem we have recently identified with using HTTP2, which can lead to high CPU and system crash.
Please add the a rule at the beginning to disable HTTP2 usage using out proxy control event.
Event: Enable Proxy Control<no HTTP2>
Where "no HTTP2" has to be created. Here you have the option "HTTP2" and the setting "Override HTTP2 support" where to set "Support HTTP2" to No.
This will solve the issue until we release the fix within the upcoming version,