Perf: Replace ContainsKey + indexer with TryGetValue to eliminate redundant hash lookups#367
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Perf: Replace ContainsKey + indexer with TryGetValue to eliminate redundant hash lookups#367PaulAndersonS wants to merge 2 commits into
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Eliminates redundant dictionary hash lookups by replacing the ContainsKey() + indexer[] anti-pattern with single TryGetValue() calls. Files changed: - Calendar/LoopingPannel/CustomSnapManager.cs (hot path during navigation) - Core/WindowOverlay/WindowOverlay.iOS.cs - Core/WindowOverlay/WindowOverlay.Windows.cs - Core/WindowOverlay/WindowOverlay.Android.cs Each occurrence previously computed the hash twice (once to check existence, once to retrieve the value). TryGetValue does both in a single lookup. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Replace Items.ToList().FindAll() with Items.Where().ToList() and Items.ToList().FirstOrDefault() with Items.FirstOrDefault(). The original code copied the entire ObservableCollection into a new List before filtering. Since ObservableCollection<T> already implements IEnumerable<T>, LINQ can operate on it directly without the intermediate full copy. Files changed: - Accordion/SfAccordion.cs (3 occurrences) - Accordion/AccordionItemView.cs (1 occurrence) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Root Cause of the Issue
Multiple locations use the
Dictionary.ContainsKey()+dictionary[key]anti-pattern, which computes the hash and locates the bucket twice for every lookup. In hot paths (Calendar navigation, WindowOverlay positioning), this adds unnecessary overhead.Description of Change
Replaced all
ContainsKey+ indexer patterns with singleTryGetValue()calls, which perform the lookup once and return both existence and value in a single operation.Files changed:
maui/src/Calendar/LoopingPannel/CustomSnapManager.cs— Called during month/year view navigation (hot path)maui/src/Core/WindowOverlay/WindowOverlay.iOS.cs— Called during overlay child positioningmaui/src/Core/WindowOverlay/WindowOverlay.Windows.cs— Called during overlay child positioningmaui/src/Core/WindowOverlay/WindowOverlay.Android.cs— Called during overlay child positioningWhy This Matters
AddChildren()is called on every view navigation; the dictionary lookups happen per visible date groupAdditional Performance Opportunities Identified
.Where().Min/Max()in hot pathsItems.ToList().FindAll()unnecessary copyCast<T>().ToList().AsReadOnly()in GetVisualChildren.Where().ToList()for Min/Max calculationsnew PathF()allocation every draw frame.Cast<T>()in loops vs direct indexingConfigureAwait(false)in library asyncScreenshots
N/A — no visual changes (performance-only improvement)