perf: Reduce allocations and eliminate delegate overhead across 5 controls

[PaulAndersonS]

Root Cause of the Issue

Multiple controls perform unnecessary memory allocations and redundant work in frequently-called paths:

• LINQ queries that allocate intermediate collections just to find a single element
• Capturing lambdas allocated on every iteration of render loops
• Missing event handler unsubscription leading to handler accumulation
• Lists created without capacity hints in per-frame rendering methods
• LINQ Select + Contains chains creating iterator objects for simple lookups

Description of Change

Five targeted performance improvements across 5 files:

1. CartesianAxisLayout.cs — GetAxisByName() used a LINQ query expression with .ToList() just to get the first matching axis. Replaced with a foreach loop that returns on first match, eliminating the list allocation entirely.

2. Calendar MonthView.cs — _specialDates.FirstOrDefault(details => ...) was called once per calendar cell (28-42 times per render frame), each time allocating a new delegate that captures the changing dateTime local. Extracted to a GetSpecialDateIcon() method using an indexed for loop.

3. ChartSeries.cs — DataLabelSettings_PropertyChanged subscribed to LabelStyle.PropertyChanged without first unsubscribing, causing duplicate handlers to accumulate each time LabelStyle was reassigned. Added the missing -= before +=.

4. PolarAreaSegment.cs — GenerateInteriorPoints() and GenerateStrokePoints() created new List<float>() with default capacity (called every render frame). Pre-allocated with calculated capacity (_pointsCount + 2) * 2 to avoid repeated array resizing.

5. SfTimePicker.cs — .Select(m => int.Parse(m)).Contains(value) allocates an iterator, a delegate, and evaluates lazily. Replaced with a static ContainsParsedValue() helper using a for loop with int.TryParse — zero allocations.

Issues Fixed

Performance optimization — no specific issue number.

Screenshots

N/A — internal allocation/performance changes with no visual impact.