Yes, we are having the same problems with CPU utilization since our upgrade this past weekend.
Just this morning we started having the agent disconnected problem which is how I found this thread. When agents fail to connect, agent logs show "Network Operation: Operation 'Head' failed. HTTP request Read Headers error, Bad SMP server version". Note: These are agents on the latest SMP 7.5 agent with sub-agents, fully updated.
We have a case open on the CPU issue (since 6/27) but haven't made any progress. Backline has a profiler trace and logs they are reviewing. I get the impression in talking with front line, this isn't the only case but they have not been able to give me a workaround or tell me they have identified the cause of the issue. I did not have these issues in our upgrade on DEV but then again I don't have 13k agents nor the number of filters, targets, SWD policies, patches, etc.
I've noticed when clients are connected, they have a very difficult time updating config. Often there is an instant reply from the server stating "Policy Request Failed: Unexpected response from the URL: https://[fqdn]/Altiris/NS/Agent/GetClientPolicies.aspx': The server is currently busy or paused (0x8004200C)". I sometimes see errors in the server log from GetClientPoliciesHandler that show the policy request failed. COM Exception errcode: 0x80000FFFF. Errors in the Windows application event log show ASP.NET 2.0 warnings: HTTPException, Request timed out.
If anyone has any suggested workarounds or any hints on the possible cause for any of these issues, I'd love to hear them. If you are having similar problems after 7.1, I'd like to hear that too so we can figure out which of these items are possibly related or not. My own troubleshooting seems to be pointing to the policy config requests being the root cause of the utilization issue but its not much more than a gut feel at this point.