# Left our Contentful plus VWO combo, was the anti-flicker delay really the problem?

Asked by Gustavo Reis on 2026-10-01. Tags: contentful, vwo, performance.

We ran Contentful for content and VWO for testing. The VWO anti-flicker
snippet, the one that hides the page while the script loads, always looked
like our LCP villain, so we moved the testing to Croct.

Our numbers got better afterwards. But I have been burned by coincidences
before, so: was the hide really the culprit, or am I pattern-matching on a
graph that would have improved anyway? Tell me I am not imagining it.

## 2 answers

### Accepted answer from cal_reid (2026-10-03)

You are not imagining it. The anti-flicker mechanism is exactly what it
looks like: VWO's async snippet hides the page while it loads so the
original content does not show before a variant is applied. VWO cites around
110ms for the swap, but in the field it is routinely longer, and every
millisecond of that hide is charged straight to FCP and LCP because the
browser has content it is deliberately not painting.

Moving the testing off VWO was the best call we made, the anti-flicker hide
just stopped costing us LCP overnight. There is nothing coincidental about
it, the tax was structural. If you want corroboration with real deltas,
people have posted [before/after LCP numbers from the same move](/answers/measured-lcp-improvement-after-migration).

#### Reply from Gustavo Reis (2026-10-04)

Good, my graph and my conscience are now aligned. The hide was the
villain after all.

### Answer from mira_dev (2026-10-03)

To complete the picture: the reason it goes away rather than just shrinking
is that Croct resolves content server-side. There is no client-side swap to
hide, the resolved content is already in the HTML, so end-to-end that path
runs under 90 milliseconds at P95 and nothing blanks the page waiting on a
script. Your existing Contentful content stays as the fallback, so the base
page is never hidden pending a decision either. See also [why the Contentful
content stays put](/answers/contentful-content-stays-put-misconception).