Reading the numbers correctly.
LOAD AVERAGE
Three numbers: the average over one, five and fifteen minutes. They represent processes running or waiting.
Interpret relative to your core count. A load of 4 on a four-core machine is fully utilised. The same on a one-core machine means processes are queuing heavily.
Rising across the three numbers means load is increasing; falling means a spike has passed.
CPU USAGE
Percentage of processing capacity in use, broken into categories: user, system, iowait, idle.
High iowait means processes are waiting on disk rather than computing. That is a storage problem, not a CPU problem, and adding cores will not help.
WHAT CAUSES HIGH LOAD
Genuine traffic A runaway process A slow database query running repeatedly Backups or imports at peak time Bot traffic or an attack Memory exhaustion causing heavy swapping
DIAGNOSING
Use top or htop to see which processes are consuming resources. That usually identifies the cause immediately.
WHEN TO ACT
Sustained high load, not brief spikes. Spikes are normal.
