Don't Clone Context in UnleashContext.ApplyStaticFields

[nathanmascitelli]

Description

When calling IUnleash.IsEnabled we end up cloning the UnleashContext. This cloning is not needed and expensive since the entire Properties dictionary needs to be cloned. This case removes the cloning.

Fixes #186

Type of change

Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Using the following benchmark (note IsEnabled2 calls the code proposed in this PR):

[MemoryDiagnoser]
public class Benchmark
{
    readonly UnleashContext context = new();
    readonly DefaultUnleash client = new(new UnleashSettings());

    public Benchmark()
    {
        // Remove this loop to test empty properties
        for (int i = 0; i < 10; i++)
        {
            context.Properties.Add(i.ToString(), i.ToString());
        }
    }

    [Benchmark(Baseline = true)]
    public bool Current() => client.IsEnabled("Moo", context);

    [Benchmark]
    public bool NoClone() => client.IsEnabled2("Moo", context);
}

The following results were obtained:

Empty Properties

Method	Mean	Error	StdDev	Ratio	Gen0	Allocated	Alloc Ratio
Current	179.3 ns	1.80 ns	1.69 ns	1.00	0.0408	512 B	1.00
NoClone	145.8 ns	1.06 ns	0.94 ns	0.81	0.0274	344 B	0.67

10 Elements in Properties

Method	Mean	Error	StdDev	Ratio	Gen0	Allocated	Alloc Ratio
Current	262.7 ns	2.64 ns	2.34 ns	1.00	0.0691	872 B	1.00
NoClone	144.8 ns	2.65 ns	3.45 ns	0.56	0.0274	344 B	0.39