Add new WriteRecords benchmark and performance fix.
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The new benchmark measures the performance of WriteRecords given an `IEnumerable<T>` records. The performance fix is to adjust `ObjectRecordWriter` to take all expressions and put them into a single block expression that writes all fields at once, instead of combining multiple expressions into a single multi-cast delegate. This results in fewer delegate invocations since it is called per record instead of per field, and only a single delegate compile. The current benchmark runs ~15% faster with the new code. Now that delegates are not combined `RecordWriter.CombineDelegates` could be removed, though I opted not to since it is on a public class and I didn't want to break compatibility. I also noted this was added since Silverlight doesn't have `Delegate.Combine` and I'm not sure if Silverlight has `Expression.Block` though given it is out of support as of Oct 2021 I figured this was ok.
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Updates
The new benchmark measures the performance of WriteRecords given an
IEnumerable<T>records. The performance fix is to adjustObjectRecordWriterto take all expressions and put them into a single block expression that writes all fields at once, instead of combining multiple expressions into a single multi-cast delegate. This results in fewer delegate invocations since it is called per record instead of per field, and only a single delegate compile. The current benchmark runs ~15% faster with the new code.Now that delegates are not combined
RecordWriter.CombineDelegatescould be removed, though I opted not to since it is on a public class and I didn't want to break compatibility. I also noted this was added since Silverlight doesn't haveDelegate.Combineand I'm not sure if Silverlight hasExpression.Blockthough given it is out of support as of Oct 2021 I figured this was ok.Before
After
Note the CPU trace shows more samples in the after but this is due to BenchmarkDotNet having a variable number of iterations per run. The actual performance per iteration is faster
