CPU 80-90% loaded

[fadmaks]

I run ph7cms on a local server and after a short time the CPU becomes 80-90% loaded. A similar situation occurs when connecting to a third-party server. There is a heavy load on the user's processor. In doing so, I used different browsers.
CPU load is also observed during program installation.
Critical CPU load does not occur immediately; you need to wait a little.
Where to look for the error?