Caching is what makes it survivable
A cached page is served without running WordPress or touching the database. That is the difference between handling ten times the traffic and falling over at three times.
Uncached, every visitor costs you a full page build. Cached, they cost almost nothing. That single distinction decides whether a spike is exciting or embarrassing.
The checklist
- Full page caching enabled and verified working
- A CDN in front of static assets
- Hosting that can scale, or headroom confirmed with your host
- Non-essential plugins disabled for the period
- Uptime monitoring with someone actually alerted
What cannot be cached
- Cart and checkout on a store
- Logged-in member areas
- Anything genuinely personalised
- Form submissions themselves
Those are your real capacity limit. Know what they can handle before the traffic arrives.
Rehearse it
Load test before the campaign, at a realistic multiple of your normal traffic. Most hosts will tell you what they can handle; testing tells you what your site can.
The rehearsal is what turns a hope into a plan.
Have a fallback
Know how to put up a static page if the site cannot cope. A fast static page with your key message is better than a site that times out.
Preparing that in advance takes an hour and it is the difference between a bad day and a lost opportunity.