Processor time.
WHAT IT MEASURES
How much processor time your account uses.
WHAT CONSUMES IT
Every page built by PHP Database queries Image processing Backups and imports Anything computational
THE SYMPTOM OF HITTING IT
Slowness, or requests failing, at busy moments.
Usually intermittent rather than constant.
WHAT TO DO FIRST
Enable caching.
A cached page serves without building anything, which removes almost all processor use for repeat visitors.
That alone resolves most CPU problems on small sites.
WHAT ELSE TO CHECK
Bot traffic, which consumes processor exactly as visitors do Plugins doing heavy work on every request Scheduled jobs running during busy periods
HOW TO IDENTIFY A CULPRIT
Compare usage spikes against your cron schedule and your traffic.
WHEN AN UPGRADE IS WARRANTED
When genuine visitor traffic exceeds what the plan provides, after caching.
Not before.
