Extensions and their cost.
WHY SHOPS ACCUMULATE PLUGINS
Each feature needs one: shipping, payment, invoicing, reports, marketing.
WHAT THAT COSTS
Every plugin adds queries, scripts and maintenance.
Shops are typically the heaviest sites on shared hosting for this reason.
WHAT TO AUDIT
Every plugin. What does it do, do you use it, is it maintained.
WHAT TENDS TO CAUSE PROBLEMS
Multiple plugins doing the same job Abandoned extensions no longer updated Anything modifying the checkout
THAT LAST ONE
Checkout modifications are the most common cause of a shop breaking after an update.
WHAT TO DO BEFORE UPDATING
Back up Update on staging first, if you have it Test the checkout afterwards, always
WHEN SOMETHING BREAKS
Deactivate the most recently updated plugin first.
WHAT TO REMOVE
Anything you cannot justify.
A shop with forty plugins has a maintenance problem.