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Web Performance Optimisation (WPO)7 min•Difficulty: Intermedio

[WPO-019] Restore fast back/forward navigation with bfcache

Find listeners, unload handlers and policies that prevent restoring a page from memory.

Ingeniería de Rendimiento AnayilUpdated: 2026-10-10

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This answer covers “[WPO-019] Restore fast back/forward navigation with bfcache”. Read it with the summary and confirm that the symptom and service match what you are experiencing. Available options can vary by plan and account setup.

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L3 technical diagnosis

Performance / configurationSeverity: Medium; high if conversion or availability is affected

User symptoms

Returning to a visited page triggers a full reload and loses interface state.

Observed code or message

DevTools reports that the page is not eligible for back/forward cache

Likely root cause

`unload` handlers, some blockers or `Cache-Control: no-store` can reduce eligibility depending on the browser. bfcache temporarily keeps a page in memory and is not the HTTP cache.

Likely-cause and resolution matrix

Follow a branch only when evidence supports it. A symptom may have more than one cause; do not change layers by guesswork.

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Prerequisites

Authorised access to the affected site, repository or service metrics.
A reproducible URL and timestamp; use staging for infrastructure changes.
A backup or rollback method for configuration and deployments.

Important warnings

Inspection commands do not authorise production changes. Do not run load tests or global purges without an approved plan.
Never store private responses in shared caches. Server changes in Anayil Panel depend on the controls available for the service and may require its administrator/provider.

Step-by-step walkthrough

1. Reproduce and narrow the issue

Returning to a visited page triggers a full reload and loses interface state. Use DevTools Application → Back/forward cache to identify the exact reason. Review lifecycle and content sensitivity before changing headers.

bash

# In Chrome DevTools: Application → Back/forward cache → Test
rg -n 'unload|beforeunload|Cache-Control' src app public

Expected output:

DevTools reports that the page is not eligible for back/forward cache

2. Apply the appropriate correction

Replace `unload` with compatible Page Lifecycle handling where appropriate and clean up listeners. Do not remove `no-store` from sensitive pages without security review; public content that must revalidate may use `no-cache`.

3. Verify the experience

Run the DevTools test and navigate back/forward in target browsers. Confirm visual restoration while sensitive data remains protected.

Expected output:

The improvement is reproducible on the affected route and profile with no new functional errors.

Troubleshooting & Solutions

DevTools reports that the page is not eligible for back/forward cache

Root cause: `unload` handlers, some blockers or `Cache-Control: no-store` can reduce eligibility depending on the browser. bfcache temporarily keeps a page in memory and is not the HTTP cache.

Resolution: Replace `unload` with compatible Page Lifecycle handling where appropriate and clean up listeners. Do not remove `no-store` from sensitive pages without security review; public content that must revalidate may use `no-cache`.

Rollback and recovery plan

Roll back only the changed directive, dependency or release using the recorded value. If 5xx errors, data exposure or session failures occur, have the operator disable the new rule and retain redacted logs for analysis.

Related runbooks in this category:

[WPO-001] Separate origin latency from browser delay7 min [WPO-002] Diagnose intermittent latency without mislabeling constant slowness7 min [WPO-003] Reduce redirect chains in the page-load path7 min

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