perf: memoize dashboard derived state to eliminate redundant renders#8
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perf: memoize dashboard derived state to eliminate redundant renders#8
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All derived values on the dashboard (filteredResults, avgPing, avgPacketLoss, avgJitter, regions, chartData, serverChartData) were recomputed inline on every React render — including renders triggered by unrelated state updates like loading toggling back to false. Each computation is now wrapped in useMemo with the tightest possible dependency array: - filteredResults: depends on results, applyDateFilter, selectedRegion - avgPing / avgPacketLoss / avgJitter: depend on filteredResults only - regions: depends on results only (not filter state) - chartData: depends on filteredResults - serverChartData: depends on filteredResults For a typical result set (~100 items) this eliminates 5 O(n) reduce passes and 2 groupBy passes on every render that doesn't change the underlying data. At 100 results the savings are modest; at the 500–1000 result scale the dashboard would hit without this change the difference is measurable. Memoization also makes the data flow explicit — it's now clear at a glance which data depends on which filters.
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Summary
All derived values on the dashboard were recomputed inline on every React render — including renders triggered by unrelated state changes like
loadingtoggling back tofalse.Wrapped every computed value in
useMemowith tight dependency arrays:filteredResultsresults,applyDateFilter,selectedRegionavgPing/avgPacketLoss/avgJitterfilteredResultsregionsresults(not filter state)chartDatafilteredResultsserverChartDatafilteredResultsFor a 100-result set this eliminates 5 O(n) reduce passes + 2 groupBy passes per extraneous render. At 500-1000 results (natural growth) the savings become measurable. The change also makes data flow explicit — easy to see which derived values depend on which inputs.
Files changed
web/src/app/dashboard/page.tsxVerification