Every account on a shared server has resource limits. They exist so that one busy site cannot slow down everyone else on the machine - including, on another day, protecting you from someone else.
Open Resource Usage in cPanel to see where you stand. Four numbers matter:
- CPU - processing time. Hitting this means your code is doing too much work per request, or you are getting more traffic than the plan is sized for.
- Physical memory - RAM. Usually a heavy plugin or an import script.
- Entry processes - how many requests are being handled at once. This is the one people hit unexpectedly. A traffic spike, or a crawler that ignores politeness, fills the slots and other visitors see a 508 error.
- I/O and IOPS - disk speed. Usually backups running or a very chatty logging plugin.
Occasional brief spikes are normal and nobody notices them. Being at the ceiling every day means something needs to change.
What to do about it: turn on page caching first, since it removes most of the per-request work outright. Then look for the specific plugin responsible - disable them one at a time and watch the graph. Then move to the current PHP version, which is meaningfully faster than versions a few years old. If usage is genuinely legitimate and simply growing, that is a good problem, and it is the point at which a VPS makes sense.
